Update .gitattributes

.gitattributes

-*.dart linguist-language=dart;
-*.m linguist-language=dart;
-*.h linguist-language=dart;
-*.kt linguist-language=dart;
-*.java linguist-language=dart;
-*.podsec linguist-language=dart;
-*.podsec linguist-language=dart;
-*.gradle linguist-language=dart;
+*.dart linguist-language=Dart;
+*.m linguist-language=Dart;
+*.h linguist-language=Dart;
+*.kt linguist-language=Dart;
+*.java linguist-language=Dart;
+*.podsec linguist-language=Dart;
+*.podsec linguist-language=Dart;
+*.gradle linguist-language=Dart;