chore: Correct Hex license identifier

Author: eproxus

src/meck.app.src

@@ -7,7 +7,7 @@
     {env, []},
 
     % Hex.pm
-    {licenses, ["Apache 2.0"]},
+    {licenses, ["Apache-2.0"]},
     {links, [
         {"Changelog", "https://github.com/eproxus/meck/blob/master/CHANGELOG.md"},
         {"GitHub", "https://github.com/eproxus/meck"}