fix: don't include trailing whitespace in code action title

The previous regex included trailing whitespace, including newline character, in the match. This meant the code action title (shown to users to trigger the action) had that trailing whitespace and newline.

This version of the regex uses a lookahead to check the `=` is followed by the end of the string or by whitespace and then the end of the string. (I.e. that the addition doesn't already have a sum.) The values in the lookahead aren't included in the match groups.

The trigger is only shown when users hover

examples/servers/code_actions.py

@@ -29,7 +29,7 @@
 )
 
 
-ADDITION = re.compile(r"^\s*(\d+)\s*\+\s*(\d+)\s*=\s*$")
+ADDITION = re.compile(r"^\s*(\d+)\s*\+\s*(\d+)\s*=(?=\s*$)")
 server = LanguageServer("code-action-server", "v0.1")