add missed .scss extensions (Hacker0x01#1098)

Author: firec0der

src/stylesheets/datepicker-cssmodules.scss

@@ -1,3 +1,3 @@
 :global {
-  @import "datepicker";
+  @import "datepicker.scss";
 }

src/stylesheets/datepicker.scss

@@ -1,5 +1,5 @@
-@import "variables";
-@import "mixins";
+@import "variables.scss";
+@import "mixins.scss";
 
 .react-datepicker-wrapper {
   display: inline-block;