Update CI to actions/checkout@v4 and actions/upload-artifact@v4 (#6786)

The old versions use a deprecated Node.js version.

Author: jwakely

.github/workflows/check.yml

@@ -22,7 +22,7 @@ jobs:
 
     steps:
       - name: checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       - name: install GNU tools
         if: matrix.cfg.os == 'macos-13'
@@ -68,7 +68,7 @@ jobs:
 
       - name: upload PDF
         if: matrix.cfg.os == 'ubuntu-22.04'
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: draft-snapshot
           path: source/std.pdf