Adding automated docker version tag for stable releases

- Added set to parse version to x.x.x format for tag. (This is the same way we parse for sentry release maps)

- Added additional build and push step for docker with parse version as tag.

.github/workflows/stable-docker.yml

@@ -40,6 +40,14 @@ jobs:
       - name: Echo csproj version
         run: echo "${{steps.get-version.outputs.assembly-version}}"
 
+      - name: Parse Version
+        run: |
+          version='${{steps.get-version.outputs.assembly-version}}'
+          newVersion=${version%.*}
+          echo $newVersion
+          echo "::set-output name=VERSION::$newVersion"
+        id: parse-version 
+
       - name: Compile dotnet app
         uses: actions/setup-dotnet@v1
         with:
@@ -75,6 +83,15 @@ jobs:
           push: true
           tags: kizaing/kavita:latest
 
+      - name: Build and push
+        id: docker_build
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          platforms: linux/amd64,linux/arm/v7,linux/arm64
+          push: true
+          tags: kizaing/kavita:${{ steps.parse-version.outputs.VERSION }}
+
       - name: Image digest
         run: echo ${{ steps.docker_build.outputs.digest }}