Avoid torch seeding in non-RL simulations (+ minor general typos + default example fixed)

[mthede]

Description

• Skip torch seeding when torch is installed but not used: Irrelevant seeding was performed and a warning was thrown about deterministic PyTorch behavior, even though simulation does not use RL. This is fixed by only setting the PyTorch seeds when learning is active.
• While at it, fixed the default example, some typos and minor rephrasing for clarity

Checklist

• Documentation updated (docstrings, READMEs, user guides, inline comments, doc folder updates etc.)
• New unit/integration tests added (if applicable)
• Changes noted in release notes (if any)
• Consent to release this PR's code under the GNU Affero General Public License v3.0

[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.99%. Comparing base (6f2857a) to head (15a7397).

Files with missing lines	Patch %	Lines
assume/common/utils.py	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #815      +/-   ##
==========================================
- Coverage   82.09%   81.99%   -0.11%     
==========================================
  Files          56       56              
  Lines        9081     9085       +4     
==========================================
- Hits         7455     7449       -6     
- Misses       1626     1636      +10     

Flag	Coverage Δ
pytest	81.99% <75.00%> (-0.11%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[reinecfi]

Looks reasonable for me. Not sure why the tests fail.