Removed optional texlive-fonts-extra

[LustigePerson]

texlive-fonts-extra seems not be be a requirement of nbconvert.
Reduces the image size by ~ 1.3 GB which will affect all images that build on the minimal-notebook image.

REPOSITORY                    TAG                 IMAGE ID            CREATED             SIZE
minimal-notebook-nofonts      latest              9641ee9dd31c        3 minutes ago       1.7GB
minimal-notebook              latest              e23d7794a410        14 minutes ago      3.01GB

I opened a issues questioning if there is any reason to keep this package. See also the comment here in PR 1013.
So this PR closes #1129.

[romainx]

Thanks for the PR.

As I said in #1129, it's OK for me. Please note that a test checks that nbconvert is working properly to convert notebook to PDF and HTML.

docker-stacks/minimal-notebook/test/test_nbconvert.py

Lines 12 to 14 in b90cce8

	@pytest.mark.parametrize("format", ["html", "pdf"])
	def test_nbconvert(container, format):
	"""Check if nbconvert is able to convert a notebook file"""

However I may be not aware of other use cases, usages.

Best

[parente]

The fonts extra package has been present in the minimal image since its original definition 5 years ago. I very likely seeded the initial list of apt packages based on brief trial and error and what we had in the all-in-one tmpnb image at the time.

I think the space savings is worth an attempt at removing it. If there is outcry, we can discuss and evaluate options (e.g., recipe, restoring it).