Xontrib-skim

- 🐞 __Fixed__
+ keybind sequences causing an error due to the parser trying to despace a list improperly

- __Changed__
+ make `X_SKIM_KEY_HIST_CWD→` consistent with `X_SKIM_KEY_HIST_Z→` and not prefill skim's query with currently typed command line text

- __Fixed__
+ 🐞 work with changed import paths in xonsh v18
+ 🐞 poetry test
- __Changed__
+ drop trying to find a binary in a nonexistent cache, which is now very costly, especially with larger `$PATH`s