Switch from anaconda to miniforge

• Update to miniforge 24.9.0 (once released) to use denylist_channels (https://docs.conda.io/projects/conda/en/latest/user-guide/configuration/settings.html#allowlist-channels-and-denylist-channels-allow-or-deny-specific-channels)
• Post installation add .condarc to block commercial channels and select conda_forge as default
• Create custom conda environment (python-common) with a selection of commonly used packages (numpy, scipy, pandas, matplotlib, ...)
• Consider removing conda update warnings (if possible)