Added a note in the documentation to indicate that the build will only work with Spark current versions.

Added a note in the documentation to indicate that the build will only work with Spark current versions.

Changed `""` into `''` to pass an empty token. Seems to be linked to this warning:
```
/opt/conda/lib/python3.8/site-packages/traitlets/traitlets.py:2195: FutureWarning: Supporting extra quotes around Unicode is deprecated in traitlets 5.0. Use '' instead of "''" – or use CUnicode.
```

Added debug information (ouput of the command line).

Add -f option with groupadd to gracefully exit when adding existing groups

Signed-off-by: Greg <werner.greg@gmail.com>

base-notebook: Update notebook to 6.1.3 and jupyterlab to 2.2.5

update to julia 1.5.0

Resolves #1131: Allow alternative Spark version

Resolve Docker lint (hadolint) errors

- Exclude `ppc64` Dockerfiles from the linting in pre-commit since we cannot check their build easily and so fix the lint errors without breaking something (already excluded in the `Makefile`)
- Fix examples Dockerfile to invert root and jovyan user instructions (Last user should not be root `DL3002`)

Allow to build `pyspark-notebook` image with an alternative Spark version.

- Define arguments for Spark installation
- Add a note in "Image Specifics" explaining how to build an image with an alternative Spark version
- Remove Toree documentation from "Image Specifics" since its support has been droped in #1115

Fix GITHUB_REPOSITORY value

Debug info for wiki push failure

Fix git-commit upstream

cd before configuring

[ci skip] Update stack READMEs

pre-commit hook + minor fixes

Pandas to 1.1

[ci skip] Fix wiki commit, 'ci skip' support

Fix git-commit var syntax

Combine jobs within workflows

Update doc, Dockerfile to test GH Actions