polkit: update to 121.

## polkit 121

### Highlights:
- new versioning
- duktape added as backend JS engine
- autotools build system removed
- new translations

### Changes since polkit 0.120:

* Simon McVittie
    * meson and testsuite fixes
* Bastien Nocera
    * add ability to create policyconfig-1.dtd file
* Xi Ruoyao
    * port to newer mozjs-91, jsauthority tweaks
* Wu Xiaotian and Gustavo Lima Chaves
    * Add duktape as javascript engine
* Nathan Follens
    * Dutch translation
* Daniel E
    * duktape fixup
* Fabrice Fontaine
    * fix build without C++
* Dan Nicholson
    * fixup in group permision checking (backend)
* Phaedrus Leeds
    * typo fix
* Adrian Vovk
    * add option (--keep-cwd) for pkexec
* Matt Turner
    * Allow --version and --help even if not setuid root
* Benedikt Ames
    * fixes in polkitagent
* Vincent Mihalkovic
    * development support

(wiz)