chore: Change note about Node 12 support

Author: nschonni

.github/ISSUE_TEMPLATE/Bug_report.md

@@ -8,7 +8,7 @@ about: If you're having an issue with installing node-sass or the compiled resul
 <!--
 Before opening an Install issue:
 
-- If you're running Node 10, you must be running node-sass 4.9.
+- If you're running Node 12, you must be running node-sass 4.12.
 - Check that the version of node-sass you're trying to install supports your version of Node by looking at the release page for that version https://github.com/sass/node-sass/releases
 - If you're running the latest versions of Node, you'll likely need the latest node-sass, we don't backport support to old versions of node-sass
 - Read the common workarounds in https://github.com/sass/node-sass/blob/master/TROUBLESHOOTING.md