Add workflow to test action automatically

.github/workflows/test.yaml

@@ -0,0 +1,30 @@
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  test-action:
+    runs-on: nix
+    name: Tests that the action works as expected
+    steps:
+      - name: Create sample file
+        run: echo "Hello, world!" > test.txt
+      - name: Upload to lgoad
+        id: upload
+        uses: https://git.colon-three.com/kodi/lgoad-upload-action@main
+        with:
+          file: test.txt
+          token: ${{ secrets.LGOAD_TOKEN }}
+          custom-machine-name: 'github-action-test-machine'
+          content-type: 'text/plain'
+          custom-name: 'test.txt'
+          use-salt: 'true'
+      - name: Print the URL
+        run: echo "The URL is ${{ steps.upload.outputs.url }}"
+      - name: Check that the file is correctly uploaded
+        run: |
+          curl -s -o test-uploaded.txt ${{ steps.upload.outputs.url }}
+          diff test.txt test-uploaded.txt
+          rm test.txt
+