Fix labeler workflow (#314)

* Switch to `pull_request_target` for labeler
    This allows PRs from forks to edit the PR

* Add action to label issues
    Separate issue and PR labeler configs

.github/issue-labeler.yml

@@ -0,0 +1,2 @@
+needs_triage:
+  - '.*'

.github/pr-labeler.yml

@@ -0,0 +1,11 @@
+needs_triage:
+  - '.*'
+  - '.*/*'
+  - '*'
+  - '*/*'
+
+docs:
+  - docs/*
+
+test:
+  - 'test/*'

.github/workflows/triage.yml

@@ -1,26 +1,33 @@
 name: Triage
 
-permissions:
-  contents: read
-  pull-requests: write
-  issues: write
-
 on:
   issues:
     types:
       - opened
+      - reopened
 
-  pull_request:
-    types:
-      - opened
+  pull_request_target:
 
 jobs:
   triage:
     runs-on: ubuntu-latest
     name: Label
 
     steps:
-      - name: Apply labels
+      - name: Label pull requests
         uses: actions/labeler@v3
         with:
           repo-token: "${{ secrets.GITHUB_TOKEN }}"
+          configuration-path: .github/pr-labeler.yml
+        if: github.event_name == 'pull_request_target'
+
+      - name: Label issues
+        # This is the latest commit in the v2.4 branch. Waiting for a 2.4.1 or newer release.
+        # https://github.com/github/issue-labeler/issues/24
+        uses: github/issue-labeler@99b4c5dda477c65f4ef08486b73c5787e1e33601
+        with:
+          repo-token: "${{ secrets.GITHUB_TOKEN }}"
+          not-before: 2021-12-07T07:00:00Z
+          configuration-path: .github/issue-labeler.yml
+          enable-versioned-regex: 0
+        if: github.event_name == 'issues'