fix: bump to latest smithy-kotlin version for codegen fixes (#1713)

Author: ianbotsf

.changes/d0acb5d7-6b4e-4163-92d0-444b89455052.json

@@ -0,0 +1,8 @@
+{
+    "id": "d0acb5d7-6b4e-4163-92d0-444b89455052",
+    "type": "bugfix",
+    "description": "Bump **smithy-kotlin** to **v1.5.15** to pick up fixes for codegen member/package collision",
+    "issues": [
+        "smithy-lang/smithy-kotlin#1444"
+    ]
+}

gradle/libs.versions.toml

@@ -12,8 +12,8 @@ atomicfu-version = "0.29.0"
 binary-compatibility-validator-version = "0.18.0"
 
 # smithy-kotlin codegen and runtime are versioned separately
-smithy-kotlin-runtime-version = "1.5.12"
-smithy-kotlin-codegen-version = "0.35.12"
+smithy-kotlin-runtime-version = "1.5.15"
+smithy-kotlin-codegen-version = "0.35.15"
 
 # codegen
 smithy-version = "1.62.0"