Explicitly instantiate matchee std::string in MatchesRegex

If this ever turns out to be a performance issue, we could use std::conditional and std::is_same to avoid copying std::strings.

Fixes #3949

PiperOrigin-RevId: 465353572
Change-Id: If2d691bccb626c692c87e006df5afe88a4ed1542

googletest/include/gtest/gtest-matchers.h

@@ -842,7 +842,7 @@ class MatchesRegexMatcher {
   template <class MatcheeStringType>
   bool MatchAndExplain(const MatcheeStringType& s,
                        MatchResultListener* /* listener */) const {
-    const std::string& s2(s);
+    const std::string s2(s);
     return full_match_ ? RE::FullMatch(s2, *regex_)
                        : RE::PartialMatch(s2, *regex_);
   }