Fix unfortunate typo generated by old sphinx-doc (#2020) in to rare d…

…ictionary

A lot of repositories contain this typo which was introduced by a bug in
a sphinx-doc template which has since been fixed. Add correction to rare dictionary.

Examples:
* mozillazg/python-pinyin#196
* jazzband/django-permission#84
* philippbosch/django-geoposition#113
* revsys/django-test-plus#117
* danjac/pyramid_storage#38
* https://github.com/tetframework/Tonnikala/pull/7`
* duerrp/pyexperiment#2

codespell_lib/data/dictionary_rare.txt

@@ -133,6 +133,7 @@ sate->state
 sates->states
 savable->saveable
 setts->sets
+shat->that, shit,
 sightly->slightly
 simplication->simplification
 singe->single