Drop nexus publishing plugin

Maven Central recently deprecated the Sonatype-style publishing, which
means the nexus publishing gradle plugin we used didn't work anymore. As
Maven Central has yet to release a replacement plugin for gradle, we
simply drop nexus publishing support here and manually upload the
archives in the meantime, which is simple enough.

We also drop the publishing CI jobs that originally aimed to automate
publishing to Maven Central, which we however never came around to use
since we didn't want to fully trust Github CI with publishing binaries
for us.

Author: tnull

.github/workflows/publish-android.yml

@@ -7,30 +7,8 @@ buildscript {
     }
 }
 
-plugins {
-    id("io.github.gradle-nexus.publish-plugin") version "1.1.0"
-}
-
 // library version is defined in gradle.properties
 val libraryVersion: String by project
 
-// These properties are required here so that the nexus publish-plugin
-// finds a staging profile with the correct group (group is otherwise set as "")
-// and knows whether to publish to a SNAPSHOT repository or not
-// https://github.com/gradle-nexus/publish-plugin#applying-the-plugin
 group = "org.lightningdevkit"
 version = libraryVersion
-
-nexusPublishing {
-    repositories {
-        create("sonatype") {
-            nexusUrl.set(uri("https://s01.oss.sonatype.org/service/local/"))
-            snapshotRepositoryUrl.set(uri("https://s01.oss.sonatype.org/content/repositories/snapshots/"))
-
-            val ossrhUsername: String? by project
-            val ossrhPassword: String? by project
-            username.set(ossrhUsername)
-            password.set(ossrhPassword)
-        }
-    }
-}

.github/workflows/publish-jvm.yml

@@ -7,30 +7,8 @@ buildscript {
     }
 }
 
-plugins {
-    id("io.github.gradle-nexus.publish-plugin") version "1.1.0"
-}
-
 // library version is defined in gradle.properties
 val libraryVersion: String by project
 
-// These properties are required here so that the nexus publish-plugin
-// finds a staging profile with the correct group (group is otherwise set as "")
-// and knows whether to publish to a SNAPSHOT repository or not
-// https://github.com/gradle-nexus/publish-plugin#applying-the-plugin
 group = "org.lightningdevkit"
 version = libraryVersion
-
-nexusPublishing {
-    repositories {
-        create("sonatype") {
-            nexusUrl.set(uri("https://s01.oss.sonatype.org/service/local/"))
-            snapshotRepositoryUrl.set(uri("https://s01.oss.sonatype.org/content/repositories/snapshots/"))
-
-            val ossrhUsername: String? by project
-            val ossrhPassword: String? by project
-            username.set(ossrhUsername)
-            password.set(ossrhPassword)
-        }
-    }
-}