Upgrade Kotlin to 2.1.21, KSP to 2.1.21-2.0.1 (#1323)

* Upgrade Kotlin to 2.1.21

* Update docs

Author: Bencodes

docs/kotlin.md

@@ -588,8 +588,8 @@ Call this in the WORKSPACE file to setup the Kotlin rules.
 | <a id="kotlin_repositories-is_bzlmod"></a>is_bzlmod |  <p align="center"> - </p>   |  `False` |
 | <a id="kotlin_repositories-compiler_repository_name"></a>compiler_repository_name |  for the kotlinc compiler repository.   |  `"com_github_jetbrains_kotlin"` |
 | <a id="kotlin_repositories-ksp_repository_name"></a>ksp_repository_name |  <p align="center"> - </p>   |  `"com_github_google_ksp"` |
-| <a id="kotlin_repositories-compiler_release"></a>compiler_release |  version provider from versions.bzl.   |  `struct(sha256 = "a118197b0de55ffab2bc8d5cd03a5e39033cfb53383d6931bc761dec0784891a", url_templates = ["https://github.com/JetBrains/kotlin/releases/download/v{version}/kotlin-compiler-{version}.zip"], version = "2.1.20")` |
-| <a id="kotlin_repositories-ksp_compiler_release"></a>ksp_compiler_release |  (internal) version provider from versions.bzl.   |  `struct(sha256 = "9f74659d447d3df29cabe0c8ee068810af313a584c1bbdde821f9894127f26e0", url_templates = ["https://github.com/google/ksp/releases/download/{version}/artifacts.zip"], version = "2.1.20-1.0.32")` |
+| <a id="kotlin_repositories-compiler_release"></a>compiler_release |  version provider from versions.bzl.   |  `struct(sha256 = "1ba08a8b45da99339a0601134cc037b54cf85e9bc0edbe76dcbd27c2d684a977", url_templates = ["https://github.com/JetBrains/kotlin/releases/download/v{version}/kotlin-compiler-{version}.zip"], version = "2.1.21")` |
+| <a id="kotlin_repositories-ksp_compiler_release"></a>ksp_compiler_release |  (internal) version provider from versions.bzl.   |  `struct(sha256 = "44e965bb067b2bb5cd9184dab2c3dea6e3eab747d341c07645bb4c88f09e49c8", url_templates = ["https://github.com/google/ksp/releases/download/{version}/artifacts.zip"], version = "2.1.21-2.0.1")` |
 
 
 <a id="versions.use_repository"></a>

src/main/starlark/core/repositories/versions.bzl

@@ -74,18 +74,18 @@ versions = struct(
         sha256 = "5ba1ac917a06b0f02daaa60d10abbedd2220d60216af670c67a45b91c74cf8bb",
     ),
     KOTLIN_CURRENT_COMPILER_RELEASE = version(
-        version = "2.1.20",
+        version = "2.1.21",
         url_templates = [
             "https://github.com/JetBrains/kotlin/releases/download/v{version}/kotlin-compiler-{version}.zip",
         ],
-        sha256 = "a118197b0de55ffab2bc8d5cd03a5e39033cfb53383d6931bc761dec0784891a",
+        sha256 = "1ba08a8b45da99339a0601134cc037b54cf85e9bc0edbe76dcbd27c2d684a977",
     ),
     KSP_CURRENT_COMPILER_PLUGIN_RELEASE = version(
-        version = "2.1.20-1.0.32",
+        version = "2.1.21-2.0.1",
         url_templates = [
             "https://github.com/google/ksp/releases/download/{version}/artifacts.zip",
         ],
-        sha256 = "9f74659d447d3df29cabe0c8ee068810af313a584c1bbdde821f9894127f26e0",
+        sha256 = "44e965bb067b2bb5cd9184dab2c3dea6e3eab747d341c07645bb4c88f09e49c8",
     ),
     KOTLIN_BUILD_TOOLS_IMPL = version(
         version = "2.1.20",
@@ -118,25 +118,25 @@ versions = struct(
         sha256 = "26d4021f6898e23b82ef953078389dd49ac2b5618ac564ade4ef87cced147b38",
     ),
     KOTLINX_SERIALIZATION_CORE_JVM = version(
-        version = "1.6.3",
+        version = "1.8.1",
         url_templates = [
             "https://repo1.maven.org/maven2/org/jetbrains/kotlinx/kotlinx-serialization-core-jvm/{version}/kotlinx-serialization-core-jvm-{version}.jar",
         ],
-        sha256 = "29c821a8d4e25cbfe4f2ce96cdd4526f61f8f4e69a135f9612a34a81d93b65f1",
+        sha256 = "3565b6d4d789bf70683c45566944287fc1d8dc75c23d98bd87d01059cc76f2b3",
     ),
     KOTLINX_SERIALIZATION_JSON = version(
-        version = "1.6.3",
+        version = "1.8.1",
         url_templates = [
             "https://repo1.maven.org/maven2/org/jetbrains/kotlinx/kotlinx-serialization-json/{version}/kotlinx-serialization-json-{version}.jar",
         ],
-        sha256 = "8c0016890a79ab5980dd520a5ab1a6738023c29aa3b6437c482e0e5fdc06dab1",
+        sha256 = "58adf3358a0f99dd8d66a550fbe19064d395e0d5f7f1e46515cd3470a56fbbb0",
     ),
     KOTLINX_SERIALIZATION_JSON_JVM = version(
-        version = "1.6.3",
+        version = "1.8.1",
         url_templates = [
             "https://repo1.maven.org/maven2/org/jetbrains/kotlinx/kotlinx-serialization-json-jvm/{version}/kotlinx-serialization-json-jvm-{version}.jar",
         ],
-        sha256 = "d3234179bcff1886d53d67c11eca47f7f3cf7b63c349d16965f6db51b7f3dd9a",
+        sha256 = "8769e5647557e3700919c32d508f5c5dad53c5d8234cd10846354fbcff14aa24",
     ),
     use_repository = _use_repository,
 )