fix(GitHub Actions): update prerelease flag and correct JAR file extension in workflow

Author: sharrlotte

.github/workflows/gradle.yml

@@ -24,7 +24,7 @@ jobs:
         with:
           repo_token: '${{ secrets.GITHUB_TOKEN }}'
           automatic_release_tag: 'latest'
-          prerelease: true
+          prerelease: false
           title: 'Release'
           files: |
-            build/libs/${{ github.event.repository.name }}.jarr
+            build/libs/${{ github.event.repository.name }}.jar