Fix action that publishes the Gradle plugin

- Set up Java so that it's available for ./gradlew to use
- Make the build-number an input for easier re-use in an emergency
- Use a working directory to hide main repository's buildSrc

.github/actions/publish-gradle-plugin/action.yml

@@ -13,6 +13,10 @@ inputs:
   gradle-plugin-publish-secret:
     description: 'Gradle publishing secret'
     required: true
+  build-number:
+    description: 'The build number to use when downloading plugin artifacts'
+    required: false
+    default: ${{ github.run_number }}
 runs:
   using: composite
   steps:
@@ -22,13 +26,13 @@ runs:
         JF_ENV_SPRING: ${{ inputs.jfrog-cli-config-token }}
     - name: Download Artifacts
       shell: bash
-      run: jf rt download --spec ${{ format('{0}/artifacts.spec', github.action_path) }} --spec-vars 'buildName=${{ format('spring-boot-{0}', inputs.plugin-version) }};buildNumber=${{ github.run_number }}'
+      run: jf rt download --spec ${{ format('{0}/artifacts.spec', github.action_path) }} --spec-vars 'buildName=${{ format('spring-boot-{0}', inputs.plugin-version) }};buildNumber=${{ inputs.build-number }}'
+    - name: Set Up Java
+      uses: actions/setup-java@v4
+      with:
+        distribution: 'liberica'
+        java-version: '17'
     - name: Publish
       shell: bash
-      run: >
-        ./gradlew publishExisting
-          -p ${{ github.action_path }}
-          -Pgradle.publish.key=${{ inputs.gradle-plugin-publish-key }}
-          -Pgradle.publish.secret=${{ inputs.gradle-plugin-publish-secret }}
-          -PbootVersion=${{ inputs.plugin-version }}
-          -PrepositoryRoot=$(pwd)/repository
+      working-directory: ${{ github.action_path }}
+      run: ${{ github.workspace }}/gradlew publishExisting -Pgradle.publish.key=${{ inputs.gradle-plugin-publish-key }} -Pgradle.publish.secret=${{ inputs.gradle-plugin-publish-secret }} -PbootVersion=${{ inputs.plugin-version }} -PrepositoryRoot=${{ github.workspace }}/repository