github: Upgrade missed deprecated actions to newer ones

These were missed in ad30b74.

The mismatch between upload-artifact and download-artifact in
ad30b74 makes the later steps
fail to download the artifacts from previous steps.

Author: mstorsjo

.github/workflows/msvcrt.yml

@@ -77,7 +77,7 @@ jobs:
           NAME=llvm-mingw-$TAG-msvcrt-$DISTRO
           mv llvm-mingw $NAME
           tar -Jcf ../$NAME.tar.xz $NAME
-      - uses: actions/upload-artifact@v3
+      - uses: actions/upload-artifact@v4
         with:
           name: linux-msvcrt-x86_64-toolchain
           path: |
@@ -120,7 +120,7 @@ jobs:
           NAME=llvm-mingw-$TAG-${{matrix.crt}}-${{matrix.arch}}
           mv llvm-mingw $NAME
           zip -9rq ../$NAME.zip $NAME
-      - uses: actions/upload-artifact@v3
+      - uses: actions/upload-artifact@v4
         with:
           name: windows-${{matrix.crt}}-${{matrix.arch}}-toolchain
           path: |