update workflows to separate build and publishing

.github/workflows/build.yml

@@ -0,0 +1,12 @@
+name: Build
+on: [push]
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-java@v1
+        with:
+          java-version: 1.8
+      - name: Build
+        run: ./gradlew build

.github/workflows/packages_publishing.yml

@@ -14,8 +14,6 @@ jobs:
           cat gradle.properties | sed -e "s/^library_version=\([0-9\.]*\)/library_version=\1-branch_$branch-build${{ github.run_number }}/" > gradle.properties.tmp
           rm gradle.properties
           mv gradle.properties.tmp gradle.properties
-      - name: Build
-        run: ./gradlew build
       - name: Publish
         run: ./gradlew publishAllPublicationsToGithubPackagesRepository --no-parallel -x signJsPublication -x signJvmPublication -x signKotlinMultiplatformPublication -x signMetadataPublication
         env: