remove GDAL as explicit dependency

[MatthiasHauthDeltares]

Issue addressed

This PR get rid of GDAL as required package during installation. This might facilitate the installation of RA2CE overall, for example if someone is struggling with GDAL wheel. The GDAL library was explicitely used in two locations of the repos:

1. function in network_utils.py which was never used: i removed it
2. function in hazard_common_functions.py I replaced GDAL with rasterio

Code of conduct

• [x] I HAVE NOT added sensitive or compromised (test) data to the repository.
• [x] I HAVE NOT added vulnerabilities to the repository.
• [x] I HAVE discussed my solution with (other) members of the RA2CE team.

What has been done?

Explain how you addressed the resolution of the related issue, what choices you made and why.

Checklist

• [x] Code is formatted using our custom black and isort definitions.
• [x] Tests are either added or updated.
• [x] Branch is up to date with master.
• [x] Updated documentation if needed.

Additional Notes (optional)

Add any additional notes or information that may be helpful.

[MatthiasHauthDeltares]

@Carsopre I removed conda-forge: GDAL from the 3 environment YML files. How can we trigger the build on this PR? it originates from my forked repo, should I open a new branch from the deltares:ra2ce instead?

[Carsopre]

@MatthiasHauthDeltares it is possible to track pull requests, but I am not comfortable on how it is presented in TC. I believe the best course of action to be a merge into a development branch where it gets "officially" taken over by "deltares". In your case you could have simply merged directly into a branch and then that PR into master. I will explore how other teams do this and discuss it further with you (and the team).