False alarms from pip's dependency resolver caused by conflicts with local packages

briefcase create android

**To Reproduce**
Steps to reproduce the behavior:
1. Go to cmd
2. execute the command: briefcase create android
4. See error:
pip's dependency resolver does not currently take into account the
packages that are installed. This behaviour is the source of the
following dependency conflicts.
toga-winforms 0.3.0.dev33 requieres toga-core==0.3.0.dev33, but you
have toga-core 0.3.0.dev34 which is incompatible.

**Expected behavior**
Lastly, Android emulator not working

**Screenshots**

**Environment:**
- Operating System: Windows 8.1 Pro
- Python version: 3.10.2
- Software versions:
- Briefcase: 0.3.7
- Toga: I think so
[tool.briefcase.app.helloworld.windows]
requires = [
'toga-winforms>=0.3.0.dev32'
- ...

**Additional context**
Add any other context about the problem here.

Start by reproducing `briefcase create android` in the reported Windows 8.1, Python 3.10.2, Briefcase 0.3.7 environment and inspect the pip resolver output. Compare the reported Toga version requirements with the generated Android project; done means the command no longer produces the misleading dependency conflict and the Android emulator behavior is explicitly verified.

Written by the indexing model from the issue text.