Do not install python-dev

[mathbunnyru]

It's an attempt to fix #1083
If everything builds fine, then we probably don't need to install python-dev manually.

[mathbunnyru]

jovyan@5daef95157f2:~$ apt-cache depends inkscape | grep python
Depends: python2:any
python2

It seems that inkscape depends on python2, but still, if we don't need something to be installed as a direct package, then let's not install it.

There is an inkscape bug, that it still needs python2, but it won't be fixed in 20.04. But as soon as 22.04 gets released, the size image will automatically shrink (https://bugs.launchpad.net/ubuntu/+source/inkscape/+bug/1735363)
Or we might delete inkscape.
Or we might use https://launchpad.net/~inkscape.dev/+archive/ubuntu/stable?field.series_filter=focal

[mathbunnyru]

@romainx @parente could you please take a look?

[romainx]

@mathbunnyru sorry for the late answer and thank you for taking care of this topic.
The reason why inkscape is installed was to fix the issue #243.
In short, inkscape is a dependency of nbconvert to treat SVG in pdf output.
If this seems to be pretty much clear, I don't know exactly when it is required.

The test test_nbconvert.py in minimal-notebook passes without the inkscape dependency installed. However we should extend the test to add a new example file with a plot in order to check if the dependency is needed / work in this condition.
If it's the case, we will probably go further on this PR.
Does that sound reasonable to you?

[mathbunnyru]

Yes, thanks, @romainx.

[romainx]

Hello,

Just pushed the PR #1182 to test nbconvert with inkscape.
Tests are OK without the explicit dependency but as expected python2 is still installed due to inkscape dependency.

$ aptitude why python2
# i   inkscape Depends  python2:any
# i A python2  Provides python2:any

So as you said I'm Ok to remove this explicit dependency even if it does not bring so much improvements as analyzed in this comment #1083 (comment)

I've asked @parente to review this also in case we missed something.

Thanks for your effort to improve the stacks 👍

[mathbunnyru]

Merged the latest master to make sure it still passes all the tests.

[romainx]

@mathbunnyru, @parente thanks for your help. Let's go for the merge.