Test tools only if they were modified

Most of the time, we are not committing changes to the tools. Move the
unit tests for the lint and generation tools to a separate PR workflow,
that is only run if anything in the tools/ folder is modified in the PR.

This saves time in the normal case.

.github/workflows/checks-main.yml

@@ -21,9 +21,6 @@ jobs:
           python -m pip install --upgrade pip
           pip install -r tools/lint/requirements.txt
 
-      - name: Test the lint tool
-        run: ./tools/lint/test/run.py
-
       - name: Lint all tests
         run: ./tools/lint/lint.py test/
 
@@ -45,9 +42,6 @@ jobs:
           python -m pip install --upgrade pip
           pip install -r tools/generation/requirements.txt
 
-      - name: Test the generation tool
-        run: ./tools/generation/test/run.py
-
       - name: Build tests
         run: |
           ./make.py clean >/dev/null

.github/workflows/checks-pr.yml

@@ -21,9 +21,6 @@ jobs:
           python -m pip install --upgrade pip
           pip install -r tools/lint/requirements.txt
 
-      - name: Test the lint tool
-        run: ./tools/lint/test/run.py
-
       - name: Identify new or changed tests
         id: changed_tests
         uses: tj-actions/changed-files@v45
@@ -66,9 +63,6 @@ jobs:
           python -m pip install --upgrade pip
           pip install -r tools/generation/requirements.txt
 
-      - name: Test the generation tool
-        run: ./tools/generation/test/run.py
-
       - name: Build tests
         run: |
           ./make.py clean >/dev/null

.github/workflows/test-tools.yml

@@ -0,0 +1,52 @@
+name: Test tools
+
+on:
+  push:
+    files:
+      - 'tools/**'
+  pull_request:
+    files:
+      - 'tools/**'
+
+jobs:
+  lint:
+    name: Test the lint tool
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.x'
+          cache: pip
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r tools/lint/requirements.txt
+
+      - name: Test the lint tool
+        run: ./tools/lint/test/run.py
+
+  generation:
+    name: Test the generation tool
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.x'
+          cache: pip
+
+      - name: Install dependencies for generation tool
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r tools/generation/requirements.txt
+
+      - name: Test the generation tool
+        run: ./tools/generation/test/run.py