chore: remove misspell (#39829)

Remove the misspell spell checker along with its `lint-spell` and
`lint-spell-fix` make targets, its CI step and its custom dictionary.

`make lint` and `make lint-fix` no longer run a spell check.

Co-authored-by: Giteabot <teabot@gitea.io>

assets/misspellings.csv

@@ -1,21 +0,0 @@
-acounts,accounts
-canidate,candidate
-comfirm,confirm
-converage,coverage
-currrently,currently
-delimeter,delimiter
-differrent,different
-exclusing,excluding
-finshed,finished
-formated,formatted
-inderect,indirect
-insuficient,insufficient
-likly,likely
-mergable,mergeable
-overrided,overridden
-priortized,prioritized
-registeration,registration
-reuqest,request
-reviwer,reviewer
-superceded,superseded
-underlaying,underlying