Work around Codespell false positive (#7924)

The Codespell checker is saying we should replace "files'" with
"file's", but this is not a real issue since the single-quote on the end
is being used as a quote and not an apostrophe. Let's tell Codespell to
ignore this.

.github/workflows/codespell.yml

@@ -13,4 +13,4 @@ jobs:
         with:
           check_filenames: true
           skip: ./.git,./conformance/third_party,*.snk,*.pb,*.pb.cc,*.pb.h,./src/google/protobuf/testdata,./objectivec/Tests,./python/compatibility_tests/v2.5.0/tests/google/protobuf/internal
-          ignore_words_list: "alow,alse,ba,cleare,copyable,cloneable,dedup,dur,errorprone,fo,fundementals,hel,importd,inout,leapyear,nd,ois,ons,parseable,process',te,testof,ue,unparseable,wasn,wee,gae,keyserver,objext,od"
+          ignore_words_list: "alow,alse,ba,cleare,copyable,cloneable,dedup,dur,errorprone,files',fo,fundementals,hel,importd,inout,leapyear,nd,ois,ons,parseable,process',te,testof,ue,unparseable,wasn,wee,gae,keyserver,objext,od"