fix gulp-sass vulnerabilities and update dependencies

vendor/fontawesome-free/css/all.css

@@ -1,5 +1,5 @@
 /*!
- * Font Awesome Free 5.8.1 by @fontawesome - https://fontawesome.com
+ * Font Awesome Free 5.8.2 by @fontawesome - https://fontawesome.com
  * License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License)
  */
 .fa,
@@ -1760,6 +1760,9 @@ readers do not read off random characters that represent icons */
 .fa-git:before {
   content: "\f1d3"; }
 
+.fa-git-alt:before {
+  content: "\f841"; }
+
 .fa-git-square:before {
   content: "\f1d2"; }
 
@@ -3485,6 +3488,9 @@ readers do not read off random characters that represent icons */
 .fa-stack-overflow:before {
   content: "\f16c"; }
 
+.fa-stackpath:before {
+  content: "\f842"; }
+
 .fa-stamp:before {
   content: "\f5bf"; }