Refactor: Modernize build and publishing workflow

- Upgraded Kotlin from 1.7.20 to 1.9.20.
- Upgraded JDK from 11 to 21 across all GitHub Actions workflows.
- Replaced the legacy `maven-publish` plugin with `com.vanniktech.maven.publish` for simplified publishing to Maven Central.
- Removed the `publishSnapshot.yml` workflow, as snapshot publishing is now managed by the new plugin.
- Updated `publishRelease.yml` to use the `publishToMavenCentral` task and new secrets (`MAVEN_CENTRAL_USERNAME`, `MAVEN_CENTRAL_PASSWORD`).
- Simplified `build.gradle.kts` by removing manual publishing and signing logic.
- Set the JVM target to "21".
- Bumped the project version to `3.1.1`.
- Removed `js` targets and related configurations.
- Added a new code style configuration file for the project (`.idea/codeStyles/Project.xml`).

.github/workflows/test.yml

@@ -12,11 +12,11 @@ jobs:
     steps:
       - name: Check out code
         uses: actions/checkout@v2
-      - name: Set up JDK 11
-        uses: actions/setup-java@v2
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
         with:
-          distribution: adopt
-          java-version: 11
+          distribution: temurin
+          java-version: '21'
 
         # Builds the release artifacts of the library
       - name: Test