test: Document non-parity between tinyformat and ConstevalFormatstring

- For "%n", which is supposed to write to the argument for printf.
- For string/integer mismatches of width/precision specifiers.

Co-Authored-By: Ryan Ofsky <ryan@ofsky.org>

test/lint/run-lint-format-strings.py

@@ -15,6 +15,8 @@ import sys
 FALSE_POSITIVES = [
     ("src/clientversion.cpp", "strprintf(_(COPYRIGHT_HOLDERS), COPYRIGHT_HOLDERS_SUBSTITUTION)"),
     ("src/test/translation_tests.cpp", "strprintf(format, arg)"),
+    ("src/test/util_string_tests.cpp", 'tfm::format(ConstevalFormatString<2>{"%*s"}, "hi", "hi")'),
+    ("src/test/util_string_tests.cpp", 'tfm::format(ConstevalFormatString<2>{"%.*s"}, "hi", "hi")'),
 ]