github: remove tiptap v1 issue template

.github/ISSUE_TEMPLATE/bug_report_v1.md

@@ -1,40 +0,0 @@
----
-name: Bug report (tiptap v1)
-about: Create a report to help us improve tiptap
-url: https://github.com/ueberdosis/tiptap/issues/new
-title: ''
-labels:
-  - bug
-  - v1
-assignees: ''
----
-
-**Description**
-A clear and concise description of what the bug is.
-
-**Steps to reproduce the bug**
-Steps to reproduce the behavior:
-1. Go to …
-2. Type in …
-3. Click on …
-4. See error message
-
-**CodeSandbox**
-I created a CodeSandbox to help you debug the issue:
-
-https://codesandbox.io/s/vue-issue-template-h0g28
-
-**Expected behavior**
-A clear and concise description of what you expected to happen.
-
-**Screenshot, video, or GIF**
-If applicable, add screenshots to help explain your problem.
-
-**Environment?**
- - operating system:
- - browser:
- - mobile/desktop:
- - tiptap version:
-
-**Additional context**
-Add any other context about the problem here.