Run pre-commit with GitHub Actions

Running pre-commit with GitHub Actions now gives us more tests and coverage

Remove duplicate GitHub Actions for merge conflicts and trailing whitespace

Remove duplicate checks for markdownlint and yamllint from the GitHub Super-Linter

Add new custom pre-commit hook running with a shell script to sort alphabetically and uniquify codespell.txt

Add new pre-commit hook to check spelling with codespell

https://github.com/codespell-project/codespell

Fix spelling

test/t/unicode.rb

@@ -1,15 +1,15 @@
 # Test of the \u notation
 
 assert('bare \u notation test') do
-  # Mininum and maximum one byte characters
+  # Minimum and maximum one byte characters
   assert_equal("\x00", "\u0000")
   assert_equal("\x7F", "\u007F")
 
-  # Mininum and maximum two byte characters
+  # Minimum and maximum two byte characters
   assert_equal("\xC2\x80", "\u0080")
   assert_equal("\xDF\xBF", "\u07FF")
 
-  # Mininum and maximum three byte characters
+  # Minimum and maximum three byte characters
   assert_equal("\xE0\xA0\x80", "\u0800")
   assert_equal("\xEF\xBF\xBF", "\uFFFF")
 
@@ -17,19 +17,19 @@ assert('bare \u notation test') do
 end
 
 assert('braced \u notation test') do
-  # Mininum and maximum one byte characters
+  # Minimum and maximum one byte characters
   assert_equal("\x00", "\u{0000}")
   assert_equal("\x7F", "\u{007F}")
 
-  # Mininum and maximum two byte characters
+  # Minimum and maximum two byte characters
   assert_equal("\xC2\x80", "\u{0080}")
   assert_equal("\xDF\xBF", "\u{07FF}")
 
-  # Mininum and maximum three byte characters
+  # Minimum and maximum three byte characters
   assert_equal("\xE0\xA0\x80", "\u{0800}")
   assert_equal("\xEF\xBF\xBF", "\u{FFFF}")
 
-  # Mininum and maximum four byte characters
+  # Minimum and maximum four byte characters
   assert_equal("\xF0\x90\x80\x80", "\u{10000}")
   assert_equal("\xF4\x8F\xBF\xBF", "\u{10FFFF}")
 end