pip-requirements.txt: Bump pytool extensions and library

pip-requirements.txt: Bump pytool extensions and library

Fixes edk2 CI failure due to VM images being updated to Python 3.11
and the old pip modules not being compatible with Python 3.11.

Updates the following pip modules:

  - edk2-pytool-library from 0.11.2 to 0.11.6
  - edk2-pytool-extensions from 0.16 to 0.19.1

Needed to fix an issue with Python 3.11 compatibility.

Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Chasel Chiu <chasel.chiu@intel.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>