Finalize workflow pins and trigger policy

Author: jeromekelleher

.github/workflows/lint.yml

@@ -2,10 +2,7 @@ name: Lint
 
 on:
   pull_request:
-  push:
-    branches: [main]
-  merge_group:
 
 jobs:
   Lint:
-    uses: tskit-dev/.github/.github/workflows/lint.yml@main
+    uses: tskit-dev/.github/.github/workflows/lint.yml@v12

.github/workflows/tests.yml

@@ -9,11 +9,11 @@ on:
 jobs:
   packaging:
     name: Python packaging
-    uses: tskit-dev/.github/.github/workflows/python-packaging.yml@main
+    uses: tskit-dev/.github/.github/workflows/python-packaging.yml@v12
 
   test:
     name: Python
-    uses: tskit-dev/.github/.github/workflows/python-tests.yml@main
+    uses: tskit-dev/.github/.github/workflows/python-tests.yml@v12
     with:
       os: ${{ matrix.os }}
       python-version: ${{ matrix.python }}