Switch to deepcell>0.12.7 requirement

[WeisLeDocto]

As detailed in #20, there might come a moment when the minimum requirement for the DeepCell library will need to be updated. However, this means integrating a mechanism for ensuring that users provide a correct DeepCell API token. All the details of what this entails are detailed in the linked issue.

This PR brings several changes enabling token integration in MyoFInDer:

• Update __main__.py to ensure the application won't start without a proper DeepCell token provided (d1858a0)
• Update Windows installer to include a field for registering a DeepCell token during installation (b7f6752)
• Update the test suite to ensure no test runs without a valid DeepCell token (a9ad5d1)
• Update GitHub Action workflows to build additional files related to the DeepCell token, and to register the token whenever needed during the build steps (8e281f0, 356f504)
• Update the installation section of the online documentation to mention the need for a DeepCell API token

The integration of the DeepCell token in MyoFInDer is far from perfect, but this implementation meets the minimal requirements IMO.

Closes #20