dev(vscode): upgrade some tasks to use uv

requirements.txt is no longer distributed, workflows should use uv.

.vscode/tasks.json

@@ -4,7 +4,7 @@
     {
       "label": "Install requirements",
       "type": "shell",
-      "command": "pip3 install -r requirements-dev.txt",
+      "command": "uv sync",
       "problemMatcher": []
     },
     {
@@ -22,14 +22,14 @@
     {
       "label": "Unit tests",
       "type": "shell",
-      "command": "pytest --cov=. --cov-config=.coveragerc --cov-report xml:coverage.xml",
+      "command": "uv run pytest --cov=. --cov-config=.coveragerc --cov-report xml:coverage.xml",
       "problemMatcher": []
     },
     {
       "label": "Reformat code",
       "type": "shell",
-      "command": "isort . &&  black .",
+      "command": "uv run ruff --select I . && uv ruff format .",
       "problemMatcher": []
     }
   ]
-}
+}