Bump xml2js, @microsoft/sp-build-web and @microsoft/sp-webpart-workbench

Bumps [xml2js](https://github.com/Leonidas-from-XIV/node-xml2js) to 0.5.0 and updates ancestor dependencies [xml2js](https://github.com/Leonidas-from-XIV/node-xml2js), [@microsoft/sp-build-web](http://aka.ms/spfx) and [@microsoft/sp-webpart-workbench](http://aka.ms/spfx). These dependencies need to be updated together.


Updates `xml2js` from 0.2.8 to 0.5.0
- [Commits](Leonidas-from-XIV/node-xml2js@0.2.8...0.5.0)

Updates `@microsoft/sp-build-web` from 1.9.1 to 1.17.2

Updates `@microsoft/sp-webpart-workbench` from 1.9.1 to 1.12.1

---
updated-dependencies:
- dependency-name: xml2js
  dependency-type: indirect
- dependency-name: "@microsoft/sp-build-web"
  dependency-type: direct:development
- dependency-name: "@microsoft/sp-webpart-workbench"
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>