Replace "Astropy" with "{{ cookiecutter.package_name }}" in BSD-3

[jgieseler]

This PR updates the BSD-3 license file:

1. replaces "Astropy" with "{{ cookiecutter.package_name }}"
2. replaces "Team" with "team"

I assume point 1. is some leftover that needs to be fixed.

Point 2. is optionally but seems more fitting in my opinion. One could think of further changing

Neither the name of the {{ cookiecutter.package_name }} team nor the names of its contributors...

to

Neither the name of {{ cookiecutter.package_name }} nor the names of its contributors...

[jgieseler]

The license file testing needed to be adjusted, too. Corresponding to the test already in place, which removed the first line of the license file from the testing, I now also skip the line where {{ cookiecutter.package_name }} is used. This is done for all different license templates, but I think it's not a big problem.

[jgieseler]

And this would also be the same at https://github.com/sunpy/package-template/blob/4fbd4808f2972d7c0673aca11932547774bc3ed2/%7B%7B%20cookiecutter.package_name%20%7D%7D/licenses/BSD3.rst?plain=1#L12

[Cadair]

@jgieseler for what it's worth the sunpy template periodically pulls in this one, so changes made here will automatically propagate down.

[jgieseler]

Good, so we don't need to change this in the sunpy version