pip: bump edk2-pytool-extensions from 0.26.3 to 0.26.4 (#217)

Bumps
[edk2-pytool-extensions](https://github.com/tianocore/edk2-pytool-extensions)
from 0.26.3 to 0.26.4.

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

pip-requirements.txt

@@ -13,7 +13,7 @@
 ##
 
 edk2-pytool-library==0.19.8
-edk2-pytool-extensions==0.26.3
+edk2-pytool-extensions==0.26.4
 edk2-basetools==0.1.39
 antlr4-python3-runtime==4.13.1
 regex==2023.10.3