Add Matcha to Supported Theme Hints (#3573)

Matcha has theming specifically for nemo, so adding it to the supported themes list!

https://vinceliuice.github.io/theme-matcha.html

Author: zquestz

src/nemo-application.c

@@ -243,7 +243,8 @@ add_fallback_mandatory_css_provider (const gchar *theme_name)
 static const char *supported_theme_hints[] = {
         "mint",
         "arc",
-        "numix"
+        "numix",
+        "matcha"
 };
 
 static gboolean