Raise error in spacy package when model name is not a valid python identifier

[pmbaumgartner]

This PR affects spacy package. It adds an error when the --name argument (or model name from the meta.json) is not a valid python identifier.

The model name needs to be a valid model identifier so that it can be included as module in the spacy_models entry point from the setup.py file.

Prior to this PR, users would get the following message if trying to package a model with an invalid name:

error in en_spacy-sst-cpu-efficiency-128 setup command: ("EntryPoint must be in 'name=module:attrs [extras]' format", 'en_spacy-sst-cpu-efficiency-128 = en_spacy-sst-cpu-efficiency-128')

Description

Example output:

$ python -m spacy package model-best output/ --name CAPS-HYPHEN-NAME

ℹ Building package artifacts: sdist

✘ Model name ('CAPS-HYPHEN-NAME') is not a valid python identifier.
This is required to correctly package the pipeline so it can be imported as a
module.
Valid characters for identifiers are ASCII A-Z, a-z, _ (underscore)
and 0-9 (except as the first character)

Types of change

enhancement

Checklist

• I confirm that I have the right to submit this contribution under the project's MIT license.
• I ran the tests, and all new and existing tests passed.
• My changes don't require a change to the documentation, or if they do, I've added all required information.

[pmbaumgartner]

Here's a summary of the three new errors/warnings:

Invalid module name

python -m spacy package model-best output/ --name invalid-module

ℹ Building package artifacts: sdist

✘ Model name ('invalid-module') is not a valid module name. This is
required so it can be imported as a module.
We recommend names that use ASCII A-Z, a-z, _ (underscore), and 0-9. 
For specific details see:
https://docs.python.org/3/reference/lexical_analysis.html#identifiers

Invalid package name

python -m spacy package model-best output/ --name invalid_päckage 

ℹ Building package artifacts: sdist

✘ Model name ('invalid_päckage') is not a permitted package name. This
is required to correctly load the model with spacy.load.
We recommend names that use ASCII A-Z, a-z, _ (underscore), and 0-9. 
For specific details see: https://www.python.org/dev/peps/pep-0426/#name

Underscore Run

python -m spacy package model-best output/ --name multiple______underscore  --build wheel

[...]
✔ Successfully created binary wheel
output/en_multiple______underscore-0.0.0/dist/en_multiple_underscore-0.0.0-py3-none-any.whl
⚠ Model name ('en_multiple______underscore') contains a run of
underscores. Runs of underscores are not significant in installed package
names.

validating wheel file name exists:

$ ls output/en_multiple______underscore-0.0.0/dist/en_multiple_underscore-0.0.0-py3-none-any.whl
output/en_multiple______underscore-0.0.0/dist/en_multiple_underscore-0.0.0-py3-none-any.whl