Update references for v4.13 release

Author: xzyfer

.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 12, you must be running node-sass 4.12.
+- If you're running Node 13, you must be running node-sass 4.13.
 - 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

CHANGELOG.md

@@ -1,3 +1,7 @@
+## v4.13.0
+
+https://github.com/sass/node-sass/releases/tag/v4.13.0
+
 ## v4.12.0
 
 https://github.com/sass/node-sass/releases/tag/v4.12.0

README.md

@@ -4,7 +4,7 @@
 
 NodeJS  | Minimum node-sass version | Node Module
 --------|--------------------------|------------
-Node 13 | (not yet release)        | 79
+Node 13 | 4.13+                    | 79
 Node 12 | 4.12+                    | 72
 Node 11 | 4.10+                    | 67
 Node 10 | 4.9+                     | 64