Also add mistmatch->mismatch

We already have mistmatches->mismatches

codespell_lib/data/dictionary.txt

diff --git a/codespell_lib/data/dictionary.txt b/codespell_lib/data/dictionary.txt
index 68990fb..6fcb50d 100644
--- a/codespell_lib/data/dictionary.txt
+++ b/codespell_lib/data/dictionary.txt
@@ -19069,6 +19069,7 @@
 misterious->mysterious
 mistery->mystery
 misteryous->mysterious
+mistmatch->mismatch
 mistmatches->mismatches
 mittigate->mitigate
 miximum->maximum