Maint: CI changes

- Only trigger on push and PR to master
- Do not push images for branches
- Add fork only workflow
- Add dependabot only workflow
- Do not trigger ci workflow from forked/dependabot PRs

.github/workflows/fork.yml

@@ -0,0 +1,40 @@
+name: Fork
+on:
+  pull_request:
+    branches:
+      - master
+    paths:
+      - .github/workflows/fork.yml
+      - cmd/**
+      - internal/**
+      - pkg/**
+      - .dockerignore
+      - .golangci.yml
+      - Dockerfile
+      - go.mod
+      - go.sum
+
+jobs:
+  verify:
+    if: github.event.pull_request.head.repo.full_name != github.repository && github.actor != 'dependabot[bot]'
+    runs-on: ubuntu-latest
+    env:
+      DOCKER_BUILDKIT: "1"
+    steps:
+      - uses: actions/checkout@v2.3.4
+
+      - name: Linting
+        run: docker build --target lint .
+
+      - name: Build test image
+        run: docker build --target test -t test-container .
+
+      - name: Run tests in test container
+        run: |
+          touch coverage.txt
+          docker run --rm \
+          -v "$(pwd)/coverage.txt:/tmp/gobuild/coverage.txt" \
+          test-container
+
+      - name: Build final image
+        run: docker build -t final-image .