Resolves failure to build binder

[julowe]

Resolves #14

Changed apt.txt to install package texlive-plain-generic (removed texlive-generic-recommended)

per this issue and the debian package texlive-generic-recommended being listed as "a transitional package for texlive-generic-recommended to ensure proper upgrade to texlive-plain-generic"

[julowe]

Next error is on postbuild (step 19) with message: (Deprecated) Installing extensions with the jupyter labextension install command is now deprecated and will be removed in a future major version of JupyterLab. and more.
Full log: build-fail-2nd-error.log

I don't think this command in postbuild is required, as I don't see it in the simple install instructions for jupyterlab-latex

Removed and binder now builds successfully.

[julowe]

For completeness, I tested the notebook. When initially opening notebook the previous run's outputs are visible and the LaTex rulez is rendered. But when running cells I get the warning:

<>:2: SyntaxWarning: invalid escape sequence '\L'
<>:2: SyntaxWarning: invalid escape sequence '\L'
[/tmp/ipykernel_82/2419648735.py:2](https://hub.2i2c.mybinder.org/tmp/ipykernel_82/2419648735.py#line=1): SyntaxWarning: invalid escape sequence '\L'
  ax.text(.5, .5, "\LaTeX $r_{ez}^{ul}$!!!!!!", fontsize=30, horizontalalignment='center')

So I added the raw prefix to the string and warning is gone and Latex Rulez is rendered.

Opening sample.tex and right-click -> 'Show LaTeX Preview' successfully renders the PDF. Editing .tex file and hitting save or preview button renders changes in pdf.

And 'jupyter-notebook-lab-extension 7.3.2' is shown as installed in the right-hand 'Extensions Manager'

This PR should now be done (or maybe too done?) let me know if you want any changes.

Here is the link to verify the mybinder build

On a side note - is there a way to make mybinder open a notebook directly (as in this link of above build) but not open in the simple interface? When I click the first link (verify the mybinder build) I get the landing page with file explorer visible and the behavior that the latex pdf preview opens in a side-pane.

When opening a file directly we land in the simple interface and the pdf preview opens in the main window with no obvious way to access the other tabs/files. Or is this behavior just happening with me (on Ubuntu 24.04.02 firefox v138.0)? (Yeah this is a tiny quibble, but I am hoping to send this notebook to non-technical users - and every extra hurdle means more questions/emails to me)