update supported cmake versions and add some tests with newer compilers (#972)

Update and test with some newer compilers and cmake versions

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

examples/enum_ostream.cpp

@@ -44,7 +44,7 @@ int main(int argc, char **argv) {
 
     // CLI11's built in enum streaming can be used outside CLI11 like this:
     using CLI::enums::operator<<;
-    std::cout << "Enum received: " << level << std::endl;
+    std::cout << "Enum received: " << level << '\n';
 
     return 0;
 }