ci: Use GITHUB_OUTPUT envvar instead of set-output command

`save-state` and `set-output` commands used in GitHub Actions are deprecated and [GitHub recommends using environment files](https://github.blog/changelog/2023-07-24-github-actions-update-on-save-state-and-set-output-commands/).

This PR updates the usage of `set-output` to `$GITHUB_OUTPUT`

Instructions for envvar usage from GitHub docs:

https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#setting-an-output-parameter

Author: arunsathiya

.github/workflows/maven-release.yml

@@ -33,7 +33,7 @@ jobs:
         gpg-passphrase: MAVEN_GPG_PASSPHRASE
     - name: Extract project version
       id: project
-      run: echo ::set-output name=version::$(mvn help:evaluate -Dexpression=project.version -q -DforceStdout)
+      run: echo "version=$(mvn help:evaluate -Dexpression=project.version -q -DforceStdout)" >> $GITHUB_OUTPUT
     - name: Build with Maven
       run: mvn -B package --file pom.xml
     - name: Publish to Maven central

.github/workflows/maven-snapshot.yml

@@ -28,7 +28,7 @@ jobs:
         run: mvn -B package --file pom.xml
       - name: Extract project version
         id: project
-        run: echo ::set-output name=version::$(mvn help:evaluate -Dexpression=project.version -q -DforceStdout)
+        run: echo "version=$(mvn help:evaluate -Dexpression=project.version -q -DforceStdout)" >> $GITHUB_OUTPUT
       - name: Publish to snapshot repo
         if: ${{ endsWith(steps.project.outputs.version, '-SNAPSHOT') }}
         run: mvn -B deploy --file pom.xml -Pgpg-sign