docs: remove Gitter from issue templates (webpack#657)

Author: ersachin3112

.github/ISSUE_TEMPLATE/BUG.md

@@ -8,10 +8,9 @@ about: Something went awry and you'd like to tell us about it.
 
 ### Bug report
 
-<!-- Please ask questions on discussions, StackOverflow or the webpack Gitter. -->
+<!-- Please ask questions on discussions or StackOverflow. -->
 <!-- https://github.com/webpack/webpack/discussions -->
 <!-- https://stackoverflow.com/questions/ask?tags=webpack -->
-<!-- https://gitter.im/webpack/webpack -->
 <!-- Issues which contain questions or support requests will be closed. -->
 
 ### Actual Behavior

.github/ISSUE_TEMPLATE/DOCS.md

@@ -20,7 +20,6 @@ Documentation Is:
 <!-- Please don't delete this template otherwise your issue will be closed immediately -->
 <!-- https://github.com/webpack/webpack/discussions -->
 <!-- https://stackoverflow.com/questions/ask?tags=webpack -->
-<!-- https://gitter.im/webpack/webpack -->
 <!-- Issues which contain questions or support requests will be closed. -->
 
 ### Your Proposal for Changes

.github/ISSUE_TEMPLATE/FEATURE.md

@@ -8,10 +8,9 @@ about: Suggest an idea for this project
 
 ### Feature Proposal
 
-<!-- Please ask questions on discussions, StackOverflow or the webpack Gitter. -->
+<!-- Please ask questions on discussions or StackOverflow. -->
 <!-- https://github.com/webpack/webpack/discussions -->
 <!-- https://stackoverflow.com/questions/ask?tags=webpack -->
-<!-- https://gitter.im/webpack/webpack -->
 <!-- Issues which contain questions or support requests will be closed. -->
 
 ### Feature Use Case

.github/ISSUE_TEMPLATE/MODIFICATION.md

@@ -8,10 +8,9 @@ about: Would you like something work differently? Have an alternative approach?
 
 ### Modification Proposal
 
-<!-- Please ask questions on discussions, StackOverflow or the webpack Gitter. -->
+<!-- Please ask questions on discussions or StackOverflow. -->
 <!-- https://github.com/webpack/webpack/discussions -->
 <!-- https://stackoverflow.com/questions/ask?tags=webpack -->
-<!-- https://gitter.im/webpack/webpack -->
 <!-- Issues which contain questions or support requests will be closed. -->
 
 ### Expected Behavior / Situation

.github/ISSUE_TEMPLATE/SUPPORT.md

@@ -4,5 +4,4 @@ about: 👉🏽 Need support, help, or advice? Don't open an issue! Head to http
 ---
 
 Hey there! If you need support, help, or advice then this is not the place to ask.
-Please visit [Discussions](https://github.com/webpack/webpack/discussions), [StackOverflow](https://stackoverflow.com/questions/tagged/webpack)
-or [the Webpack Gitter](https://gitter.im/webpack/webpack) instead.
+Please visit [GitHub Discussions](https://github.com/webpack/webpack/discussions) or [StackOverflow](https://stackoverflow.com/questions/tagged/webpack) instead.