Update issue templates

Author: xdd666t

.github/ISSUE_TEMPLATE/custom.md

@@ -0,0 +1,18 @@
+---
+name: Custom issue template
+about: Describe this issue template's purpose here.
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+### Version Information
+- Flutter version: [e.g. v3.22.0]
+- flutter_smart_dialog version: [e.g. v4.6.6]
+
+### Describe the bug/requirement
+Please describe the bug or requirement accurately
+
+### Problem demo
+<!-- if you cannot provide the simplest demo (executable main file) that can reproduce the problem, I will refuse to solve your issue -->