CI: add/update build action

.github/workflows/build.yml

@@ -0,0 +1,36 @@
+name: build
+
+on:
+  push:
+    branches:
+      - main
+    tags:
+      - "*-[0-9]+.*"
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Java
+        uses: actions/setup-java@v3
+        with:
+          java-version: '8'
+          distribution: 'zulu'
+          cache: 'maven'
+      - name: Set up CI environment
+        run: .github/setup.sh
+      - name: Execute the build
+        run: .github/build.sh
+        env:
+          GPG_KEY_NAME: ${{ secrets.GPG_KEY_NAME }}
+          GPG_PASSPHRASE: ${{ secrets.GPG_PASSPHRASE }}
+          MAVEN_USER: ${{ secrets.MAVEN_USER }}
+          MAVEN_PASS: ${{ secrets.MAVEN_PASS }}
+          OSSRH_USER: ${{ secrets.OSSRH_USER }}
+          OSSRH_PASS: ${{ secrets.OSSRH_PASS }}
+          SIGNING_ASC: ${{ secrets.SIGNING_ASC }}