Limit bug reports and enhancement suggestions to sponsors

.github/ISSUE_TEMPLATE/bug_report.md

@@ -1,6 +1,6 @@
 ---
-name: Report a bug
-about: Create a report about something that is not working properly
+name: Report a bug (sponsors-only)
+about: "Create a report about something that is not working properly. Note: tickets opened by non-sponsors will be automatically closed"
 labels: bug
 ---
 

.github/ISSUE_TEMPLATE/enhancement.md

@@ -1,6 +1,6 @@
 ---
-name: Suggest an enhancement
-about: "Suggest an idea for this project. Note: priority will be given to suggestions made by sponsors"
+name: Suggest an enhancement (sponsors-only)
+about: "Suggest an idea for this project. Note: tickets opened by non-sponsors will be automatically closed"
 labels: enhancement
 ---
 

.github/ISSUE_TEMPLATE/question.md

@@ -1,5 +1,5 @@
 ---
 name: Ask a question or request support (sponsors-only)
-about: "Important: only sponsors can ask a question on GitHub. If you're not a sponsor, please post your question on StackOverflow"
+about: "Ask a question about this project or request support. Note: tickets opened by non-sponsors will be automatically closed"
 labels: question
 ---