Split Python linting into separate jobs.

This is just the first step to prove the concept. Most of the work done
in our workflows can be split into separate jobs to parallelize the
workflow. This will also make the checks page more readable.

This change alone probably won't speed up CI much.

.github/workflows/black.yml

@@ -1,13 +0,0 @@
-name: Lint
-
-on: [push, pull_request]
-
-jobs:
-  lint:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - uses: actions/setup-python@v2
-      - uses: psf/black@stable
-        with:
-          args: ". --check"

.github/workflows/build.yml

@@ -3,6 +3,9 @@ name: Build
 on: [push, pull_request]
 
 jobs:
+  lint:
+    uses: ./.github/workflows/lint.yml
+
   build:
     runs-on: windows-latest
     steps:
@@ -16,9 +19,6 @@ jobs:
       - name: Set up JS environment
         uses: ./.github/actions/setup-liberation-js
 
-      - name: mypy
-        uses: ./.github/actions/mypy
-
       - name: Set build number
         run: |
           [IO.File]::WriteAllLines($pwd.path + "\resources\buildnumber", $env:GITHUB_RUN_NUMBER)

.github/workflows/lint.yml

@@ -0,0 +1,28 @@
+name: Python lint
+
+on: workflow_call
+
+jobs:
+  black:
+    name: Black
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+      - uses: psf/black@stable
+        with:
+          args: ". --check"
+
+  mypy:
+    name: Type checking
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          submodules: true
+
+      - name: Set up Python environment
+        uses: ./.github/actions/setup-liberation-python
+
+      - name: mypy
+        uses: ./.github/actions/mypy

.github/workflows/release.yml

@@ -5,6 +5,9 @@ on:
     tags: ["*"]
 
 jobs:
+  lint:
+    uses: ./.github/workflows/lint.yml
+
   build:
     runs-on: windows-latest
     steps:
@@ -18,9 +21,6 @@ jobs:
       - name: Set up JS environment
         uses: ./.github/actions/setup-liberation-js
 
-      - name: mypy
-        uses: ./.github/actions/mypy
-
       - name: Finalize build
         run: |
           New-Item -ItemType file resources\final