python3: 3.9 -> 3.10

Defaults python3 to Python 3.10 while still keeping Python 3.9 around
until after the 22.11 release.

pkgs/top-level/all-packages.nix

@@ -14426,11 +14426,11 @@ with pkgs;
   # available as `pythonPackages.tkinter` and can be used as any other Python package.
   # When switching these sets, please update docs at ../../doc/languages-frameworks/python.md
   python2 = python27;
-  python3 = python39;
+  python3 = python310;
 
   # pythonPackages further below, but assigned here because they need to be in sync
   python2Packages = dontRecurseIntoAttrs python27Packages;
-  python3Packages = dontRecurseIntoAttrs python39Packages;
+  python3Packages = dontRecurseIntoAttrs python310Packages;
 
   pypy = pypy2;
   pypy2 = pypy27;
@@ -14472,6 +14472,12 @@ with pkgs;
     bluezSupport = true;
     x11Support = true;
   };
+  python310Full = python310.override {
+    self = python310Full;
+    pythonAttr = "python310Full";
+    bluezSupport = true;
+    x11Support = true;
+  };
 
   pythonInterpreters = callPackage ./../development/interpreters/python { };
   inherit (pythonInterpreters) python27 python37 python38 python39 python310 python311 python3Minimal pypy27 pypy38 pypy37 rustpython;