Refactor GitHub Actions workflows

-  Remove unnecessary lines in deploy.yml
-  Rename `validate-pr` job to `validate-labels` in pr_lint.yml and add concurrency settings
-  Modify the way of getting pull request data in pr_lint.yml
-  Add `validate-code`, `validate-docker-build`, and `validate-branch` jobs in pr_lint.yml with proper concurrency settings
-  In `validate-docker-build`, implement Docker image building and caching
-  Check branch name with version in `validate-branch` job

.github/workflows/deploy.yml

@@ -108,7 +108,6 @@ jobs:
           cache-to: type=gha,mode=max
           platforms: linux/amd64,linux/arm64,linux/arm/v7
 
-
   release:
     runs-on: ubuntu-latest
     if: ${{ needs.lint.outputs.is_release }}
@@ -141,7 +140,6 @@ jobs:
 
       - name: Release
         uses: softprops/action-gh-release@v1
-
         with:
           body: |
             Docker image: [`${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ steps.get_version.outputs.version }}`](https://github.com/jag-k/owntinfoil/pkgs/container/owntinfoil/${{ steps.docker_build.outputs }}?tag=${{ steps.get_version.outputs.version }})

.github/workflows/pr_lint.yml

@@ -4,16 +4,21 @@ on:
   pull_request:
 
 jobs:
-  validate-pr:
+  validate-labels:
     runs-on: ubuntu-latest
+    concurrency:
+      group: validate-pr
+      cancel-in-progress: true
     steps:
       - name: Check labels
         uses: actions/github-script@v7
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           # language=JavaScript
           script: |
-            const { data: pullRequest } = await github.rest.pulls.get({
+            const {
+              data: pullRequest
+            } = await github.rest.pulls.get({
               owner: context.repo.owner,
               repo: context.repo.repo,
               pull_number: context.issue.number
@@ -37,7 +42,9 @@ jobs:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           # language=JavaScript
           script: |
-            const { data: pullRequest } = await github.rest.pulls.get({
+            const {
+              data: pullRequest
+            } = await github.rest.pulls.get({
               owner: context.repo.owner,
               repo: context.repo.repo,
               pull_number: context.issue.number
@@ -53,7 +60,9 @@ jobs:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           # language=JavaScript
           script: |
-            const { data: pullRequest } = await github.rest.pulls.get({
+            const {
+              data: pullRequest
+            } = await github.rest.pulls.get({
               owner: context.repo.owner,
               repo: context.repo.repo,
               pull_number: context.issue.number
@@ -65,6 +74,9 @@ jobs:
 
   validate-code:
     runs-on: ubuntu-latest
+    concurrency:
+      group: validate-pr
+      cancel-in-progress: true
     outputs:
       version: ${{ steps.get_version.outputs.version }}
     steps:
@@ -92,11 +104,41 @@ jobs:
         run: |
           echo "version=$(poetry version -s)" >> $GITHUB_OUTPUT
 
+  validate-docker-build:
+    runs-on: ubuntu-latest
+    needs: validate-code
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Cache Docker layers
+        uses: actions/cache@v4
+        with:
+          path: /tmp/.buildx-cache
+          key: ${{ runner.os }}-buildx-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-buildx-
+
+      - name: Build Docker image
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          push: false
+          tags: user/app:pr-${{ github.event.pull_request.number }}
+          cache-from: type=local,src=/tmp/.buildx-cache
+          cache-to: type=local,dest=/tmp/.buildx-cache
+          platforms: linux/amd64,linux/arm64,linux/arm/v7
+
   validate-branch:
     runs-on: ubuntu-latest
     needs:
       - validate-code
-
+    concurrency:
+      group: validate-pr
+      cancel-in-progress: true
     if: startsWith(github.head_ref, 'release/')
     steps:
       - name: Check branch name with version