.github: Bump upload-artifact to v4 in CI to solve deprecation errors

Signed-off-by: Alex Jones <alex.jones@lowrisc.org>

Author: AlexJones0

.github/workflows/build_test.yaml

@@ -41,7 +41,7 @@ jobs:
           scripts/opentitan/swexit.py -t earlgrey -b 0x80 -o build-clang/exit_eg.bin
           scripts/opentitan/swexit.py -t darjeeling -b 0x80 -o build-clang/exit_dj.bin
       - name: Upload QEMU binary artifacts
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: qemu-bin
           path: |
@@ -58,7 +58,7 @@ jobs:
             build-clang/trace/*.h \
             build-clang/compile_commands.json
       - name: Upload QEMU source artifacts
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: qemu-src
           path: qemu-src-artifact.tar.gz