Fix lint W1404 implicit-str-concat in LoadAuth.get_tok warning

CI saltpylint flagged `salt/auth/__init__.py:253` with
`W1404(implicit-str-concat)`. The two adjacent string literals on
that line are the result of black collapsing what was originally a
two-line string onto a single line, which saltpylint reads as a
missing comma. Merge them into a single string literal; the message
remains under 88 columns so black leaves it alone.

Refs: #69073

Author: co-cy

salt/auth/__init__.py

@@ -250,7 +250,7 @@ def get_tok(self, tok):
             # around makes every subsequent ``get_tok`` for the same
             # id keep failing.
             log.warning(
-                "Token %r could not be deserialized; removing it from the " "store.",
+                "Token %r could not be deserialized; removing it from the store.",
                 tok,
             )
             self.rm_token(tok)