github-ci: bump upload-artifact@v3 to @v4

Author: GeorgeTsagk

.github/workflows/main.yaml

@@ -258,7 +258,7 @@ jobs:
         run: 7z a logs-itest.zip itest/**/*.log
 
       - name: Upload log files on failure
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         if: ${{ failure() }}
         with:
           name: logs-itest
@@ -286,7 +286,7 @@ jobs:
         run: 7z a logs-itest-postgres.zip itest/**/*.log
 
       - name: Upload log files on failure
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         if: ${{ failure() }}
         with:
           name: logs-itest-postgres