WEB: Add 2.1 to the switcher (#54874)

Author: lithomas1

web/pandas/versions.json

@@ -5,10 +5,15 @@
         "url": "https://pandas.pydata.org/docs/dev/"
     },
     {
-        "name": "2.0 (stable)",
-        "version": "2.0",
+        "name": "2.1 (stable)",
+        "version": "2.1",
         "url": "https://pandas.pydata.org/docs/"
     },
+    {
+        "name": "2.0",
+        "version": "2.0",
+        "url": "https://pandas.pydata.org/pandas-docs/version/2.0"
+    },
     {
         "name": "1.5",
         "version": "1.5",