feat: introduce linter to run on PR builds

In order to catch a variaty of small and quick to happen mistakes, there
is now an additional action in place which runs a linter on the PR
content.

fixes k8sgpt-ai#330

.github/workflows/golangci_lint.yaml

@@ -0,0 +1,18 @@
+name: Run golangci-lint
+
+on:
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  golangci-lint:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code into the Go module directory
+        uses: actions/checkout@v3
+
+      - name: golangci-lint
+        uses: reviewdog/action-golangci-lint@v2
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          reporter: github-pr-check