Use .codespellrc file to configure spell check

The recent 2.0.0 release of the codespell tool used by the "Spell Check" CI workflow added support for configuring the
tool via a configuration file. Use of this file allows the spell check to easily be run by contributors locally with the
identical configuration as will be done in the CI. It replaces extras/codespell-ignore-words-list.txt.

Author: per1234

.codespellrc

@@ -0,0 +1,7 @@
+# See: https://github.com/codespell-project/codespell#using-a-config-file
+[codespell]
+# In the event of a false positive, add the problematic word, in all lowercase, to a comma-separated list here:
+ignore-words-list = ,
+check-filenames =
+check-hidden =
+skip = ./.git,./src/libmodbus

.github/workflows/spell-check.yml

@@ -18,9 +18,3 @@ jobs:
       # See: https://github.com/codespell-project/actions-codespell/blob/master/README.md
       - name: Spell check
         uses: codespell-project/actions-codespell@master
-        with:
-          check_filenames: true
-          check_hidden: true
-          # In the event of a false positive, add the word in all lower case to this file:
-          ignore_words_file: extras/codespell-ignore-words-list.txt
-          skip: ./.git,./src/libmodbus