[BUG][Python] Incorrect Python package name for 4.0.3

[daviddavis]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• What's the version of OpenAPI Generator used?
• Have you search for related issues/PRs?
• What's the actual output vs expected output?
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Description

Python package name is wrong for openapi-cli v4.0.3.

openapi-generator version

4.0.3

Command line used for generation

    docker run -u $(id -u) --rm -v ${PWD}:/local openapitools/openapi-generator-cli generate \
        -i /local/api.json \
        -g python \
        -o /local/pulp_file-client \
        -DpackageName=pulpcore.client.pulp_file \
        -DprojectName=pulp_file-client \
        -DpackageVersion=0.1.0b1 \
        --skip-validate-spec \
        --strict-spec=false

Steps to reproduce

Use the above command to generate a client.

With 4.0.2:

cat pulp_file-client/setup.py | grep NAME
NAME = "pulp_file-client"
    name=NAME,

With 4.0.3:

cat pulp_file-client/setup.py | grep NAME
NAME = "openapi-client"
    name=NAME,

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[dkliban]

This is not a language specific bug. I am seeing the same behavior for Ruby clients.

[wing328]

Please use --additional-properties instead of -D.