Remove Python 2 references from documentation

[Copilot]

Python 2 is no longer supported. This PR removes all Python 2-specific references from the documentation.

Changes

• docs/installing.rst: Removed obsolete text about setup.py sorting between Python 2/3 packages
• docs/configuration/porting_from_dsa.rst: Fixed Python 2 print statement syntax to Python 3

# Before
print 'New session saved {}'.format(new_sess.pk)

# After
print('New session saved {}'.format(new_sess.pk))

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• docs.python.org
  • Triggering command: /usr/bin/python3 /home/REDACTED/.local/bin/sphinx-build -b html -d _build/doctrees . _build/html (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

Review the documentation for Python 2 specific topics and remove them, the Python 2 is no longer supported.

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[Copilot]

Pull Request Overview

This PR modernizes the documentation by removing outdated Python 2 references and updating code examples to use Python 3 syntax.

• Removes references to Python 2/3 package differentiation in the installation documentation
• Updates print statement to use Python 3 function syntax in the migration script example

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
docs/installing.rst	Removes outdated documentation about Python 2/3 package handling in setup.py
docs/configuration/porting_from_dsa.rst	Updates print statement to Python 3 function syntax in migration script example

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