Preemptive fixing `postBuild`

[chainsawriot]

like #11 but for quarto-dev/quarto-cli#12162

Long story short is that repo2docker is using jupyterlab 4 but quarto cannot detect that and assume it's still jupyterlab 3 and hardcodes jupyterlab-quarto to 0.1.45. Which leads to crazy rendering of Jupyter notebook, e.g. https://mybinder.org/v2/gh/schochastics/MH_netAnaR/HEAD?urlpath=%2Fdoc%2Ftree%2Findex.ipynb

We should remove the hardcoded jupyterlab-quarto==0.1.45 (if detected) to just jupyterlab-quarto.