Make --override parsing a little more forgiving

Handle option values with = in them even if the user uses a space
as a separator rather than an =

kitty/cli.py

@@ -770,7 +770,8 @@ def parse_args(
 def create_opts(args: CLIOptions, accumulate_bad_lines: Optional[List[BadLineType]] = None) -> KittyOpts:
     from .config import load_config
     config = tuple(resolve_config(SYSTEM_CONF, defconf, args.config))
-    overrides = (a.replace('=', ' ', 1) for a in args.override or ())
+    pat = re.compile(r'^([a-zA-Z0-9_ ]+)=')
+    overrides = (pat.sub(r'\1 ', a) for a in args.override or ())
     opts = load_config(*config, overrides=overrides, accumulate_bad_lines=accumulate_bad_lines)
     return opts