chore(renovate): Don't pin python version to the latest

Part-of: <https://dev.funkwhale.audio/funkwhale/funkwhale/-/merge_requests/2594>

.gitlab/renovate.json

@@ -70,6 +70,10 @@
         ],
         "fileFilters": ["changes/changelog.d/postgres.update"]
       }
+    },
+    {
+      "matchPackageNames": ["python"],
+      "rangeStrategy": "widen"
     }
   ]
 }

changes/changelog.d/renovate-python.misc

@@ -0,0 +1 @@
+Make renovate not pinning the python version to the latest one