Add a regression template

.github/ISSUE_TEMPLATE/regression.yaml

@@ -0,0 +1,66 @@
+name: 🐞 Regression
+description: File a recent regression
+title: "[REGRESSION] <title>"
+labels: [Bug, Needs Triage]
+body:
+- type: checkboxes
+  attributes:
+    label: Is there an existing issue for this?
+    description: Please [search the issues](https://github.com/mastodon/mastodon-ios/issues) to see if an issue already exists for the bug you encountered. Please check also the [closed issues](https://github.com/mastodon/mastodon-ios/issues?q=is%3Aissue+is%3Aclosed). 
+    options:
+    - label: I have searched the issues (both open and closed)
+      required: true
+- type: textarea
+  attributes:
+    label: Current Behavior
+    description: A concise description of what you're experiencing.
+    value: |
+       - As of version/build:
+  validations:
+    required: false
+- type: textarea
+  attributes:
+    label: Expected Behavior
+    description: A concise description of what you expected to happen.
+    value: |
+      - Was last working in version/build: 
+  validations:
+    required: false
+- type: textarea
+  attributes:
+    label: Steps To Reproduce
+    description: Steps to reproduce the behavior.
+    placeholder: |
+      1. In this environment...
+      2. With this config...
+      3. Tap '...'
+      4. See error...
+  validations:
+    required: false
+- type: textarea
+  attributes:
+    label: Environment
+    description: |
+      You can check the version and build number in the bottom of in-app settings.
+      examples:
+        - **Device**: iPhone X
+        - **OS**: iOS 15.3
+        - **Version**: `2023.15`
+        - **Build**: 103
+    value: |
+        - Device:
+        - OS:
+        - Version:
+        - Build:
+    render: markdown
+  validations:
+    required: false
+- type: textarea
+  attributes:
+    label: Anything else?
+    description: |
+      The server domain? Post links? Anything that will give us more context about the issue you are encountering!
+
+      Tip: You can attach images or video or log files by clicking this area to highlight it and then dragging files in.
+  validations:
+    required: false