ci: upgrade actions/upload-artifact from v3 to v4 (#116)

v3 is deprecated and auto-failing since April 2024:
https://github.blog/changelog/2024-04-16-deprecation-notice-v3-of-the-artifact-actions/

This was blocking all PR checks on Windows.

Author: TimeToBuildBob

.github/workflows/build.yml

@@ -13,10 +13,10 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-20.04, windows-latest, macOS-12]
+        os: [ubuntu-latest, windows-latest, macos-latest]
         python_version: [3.9]
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
       with:
         submodules: 'recursive'
     - name: Set up Python
@@ -51,15 +51,15 @@ jobs:
       run: |
           dist/aw-watcher-window/aw-watcher-window --help
     - name: Upload package
-      uses: actions/upload-artifact@v3
+      uses: actions/upload-artifact@v4
       with:
         name: aw-watcher-window-${{ runner.os }}-py${{ matrix.python_version }}
         path: dist/aw-watcher-window
 
   typecheck:
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
       with:
         submodules: 'recursive'
     - name: Set up Python