ci: set-environment reusable workflow

.github/workflows/set-environment.yml

@@ -0,0 +1,11 @@
+on:
+  workflow_call:
+
+jobs:
+  set-environment:
+    env:
+      ENVIRONMENT: ${{ github.event_name == 'pull_request_target' && github.event.pull_request.head.repo.full_name != github.repository && 'pr-from-fork' || 'none' }}
+    environment: ${{ env.ENVIRONMENT }}
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo "Environment set as '${{ env.ENVIRONMENT }}'"

.github/workflows/test-set-environment.yml

@@ -0,0 +1,9 @@
+name: 'Test set-environment'
+
+jobs:
+  test-set-environment:
+    uses: ./.github/workflows/set-environment.yml
+  some-job:
+    runs-on: ubuntu-latest
+    steps:
+      - run: echo "blah"

act-event.json

@@ -0,0 +1,9 @@
+{
+	"pull_request": {
+		"head": {
+			"repo": {
+				"full_name": "zachstence/evidence"
+			}
+		}
+	}
+}