pip: update edk2-pytool-extensions requirement from ~=0.20.0 to ~=0.21.7

Updates the requirements on [edk2-pytool-extensions](https://github.com/tianocore/edk2-pytool-extensions) to permit the latest version.
- [Release notes](https://github.com/tianocore/edk2-pytool-extensions/releases)
- [Commits](https://github.com/tianocore/edk2-pytool-extensions/compare/v0.20.0...v0.21.7)

---
updated-dependencies:
- dependency-name: edk2-pytool-extensions
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>
diff --git a/pip-requirements.txt b/pip-requirements.txt
index 4ffcadd..e256d98 100644
--- a/pip-requirements.txt
+++ b/pip-requirements.txt
@@ -13,7 +13,7 @@
 ##

 

 edk2-pytool-library==0.12.1

-edk2-pytool-extensions~=0.20.0

+edk2-pytool-extensions~=0.21.7

 edk2-basetools==0.1.39

 antlr4-python3-runtime==4.7.1

 lcov-cobertura==2.0.2