Update conda virtual environment example

Update python_virtual_environments.md: insert missing line. When executing this example, there is a conda init error raised if this line was not executed previously.

Ich habe es gerade durchgespielt und diese Zeile fehlt im Beispiel. Mit der Zeile ist es nun stand-alone ausführbar.

assigned to @mflehmig--tu-dresden.de

requested review from @notr584d--tu-dresden.de

approved this merge request

added 1 commit

• ac6481e8 - Update Software version

Compare with previous version

merged

mentioned in commit 7ff00b7c