Add GitHub workflow for linting nginx.conf and security-headers.conf

Signed-off-by: June <zanthed@riseup.net>

.github/workflows/nginx.yml

@@ -0,0 +1,19 @@
+name: Lint nginx configuration
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  static:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - run: sudo apt-get update
+    - run: sudo apt-get -y install python3-pip python3-setuptools
+    - run: pip3 install wheel
+    - run: pip3 install gixy
+    - run: ~/.local/bin/gixy nginx/nginx.conf