update to upload-artifact@v4

Author: pisaiah

.github/workflows/blank.yml

@@ -47,7 +47,7 @@ jobs:
            mv $ZIPNAME ../
            cd ..
       - name: Create artifact
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: linux
           path: vpaint_linux.zip
@@ -86,7 +86,7 @@ jobs:
            mv $ZIPNAME ../
            cd ..
       - name: Create artifact
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: macos
           path: vpaint_macos.zip
@@ -146,7 +146,7 @@ jobs:
 # https://superuser.com/a/1336434/194881
 # It is needed, because `zip` is not installed by default :-|
       - name: Create artifact
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: windows
           path: vpaint_windows.zip