Fix environment field in issue templates

The render: markdown causes formatting problems (too long lines) in the
post, at least sometimes.

.github/ISSUE_TEMPLATE/bug_report.yml

@@ -40,7 +40,6 @@ body:
         - OS:
         - Device:
         - Compiler:
-    render: markdown
   validations:
     required: true
 

.github/ISSUE_TEMPLATE/other_issue.yml

@@ -51,7 +51,6 @@ body:
         - OS:
         - Device:
         - Browser:
-    render: markdown
   validations:
     required: true