Template for users to report resolver failures

.github/ISSUE_TEMPLATE/resolver-failure.md

@@ -0,0 +1,21 @@
+---
+name: Dependency resolver failures / errors
+about: Report when the pip dependency resolver fails
+labels: ["K: UX", "K: crash", "C: new resolver", "C: dependency resolution"]
+
+---
+
+<!-- 
+  Please provide as much information as you can about your failure, so that we can understand the root cause.
+
+  For example, if you are installing packages from pypi.org, we'd like to see:
+
+  - Your terminal output
+  - Any inputs to pip, for example:
+    - any package requirements: any CLI arguments and/or your requirements.txt file
+    - any already installed packages, outputted via `pip freeze`
+
+  It would be great if you could also include your dependency tree. For this you can use pipdeptree: https://pypi.org/project/pipdeptree/
+
+  For users installing packages from a private repository or local directory, please try your best to describe your setup.   We'd like to understand how to reproduce the error locally, so would need (at a minimum) a description of the packages you are trying to install, and a list of dependencies for each package.
+-->