fix lints

Author: Carreau

.github/workflows/ci.yml

@@ -125,7 +125,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest]
-        python-version: ["3.9"]
+        python-version: ["3.10"]
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -156,7 +156,7 @@ jobs:
         uses: jupyterlab/maintainer-tools/.github/actions/base-setup@v1
         with:
           dependency_type: minimum
-          python_version: "3.9"
+          python_version: "3.10"
 
       - name: List installed packages
         run: |

.github/workflows/downstream.yml

@@ -95,7 +95,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
-          python-version: "3.9"
+          python-version: "3.10"
           architecture: "x64"
       - name: Install System Packages
         run: |
@@ -127,7 +127,7 @@ jobs:
       - name: Setup Python
         uses: actions/setup-python@v5
         with:
-          python-version: "3.9"
+          python-version: "3.10"
           architecture: "x64"
       - name: Install System Packages
         run: |

ipykernel/jsonutil.py

@@ -156,7 +156,7 @@ def json_clean(obj):  # pragma: no cover
         for k, v in obj.items():
             out[str(k)] = json_clean(v)
         return out
-    if isinstance(obj, (datetime, date)):
+    if isinstance(obj, datetime | date):
         return obj.strftime(ISO8601)
 
     # we don't understand it, it's probably an unserializable object