Fixes Python installation breakage for Ubuntu Focal.

[0spinboson]

Fix Python installation and analytics API for Ubuntu focal. Replace deadsnakes PPA with Python-from-source build to fix Ubuntu Focal compatibility.

• Add dynamic version fetching for latest Python patch releases,
• Add comprehensive Python build dependencies for source compilation,
• Include build caching optimizations for faster subsequent builds.
• Also small fix for analytics.daily_usage function to handle dict returns properly.

This resolves build failures on Ubuntu Focal where deadsnakes PPA no longer provides packages, and fixes 'str has no attribute max' errors in analytics API.

[Aradhya-Tripathi]

We are now building on jammy regardless

https://github.com/frappe/press/blob/develop/press/docker/Dockerfile#L2C1-L3C1

[codecov]

Codecov Report

❌ Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 44.96%. Comparing base (5ee0698) to head (a7036ad).
⚠️ Report is 33 commits behind head on develop.

Files with missing lines	Patch %	Lines
press/api/analytics.py	0.00%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3583      +/-   ##
===========================================
- Coverage    44.96%   44.96%   -0.01%     
===========================================
  Files          709      709              
  Lines        47911    47920       +9     
===========================================
+ Hits         21544    21547       +3     
- Misses       26367    26373       +6     

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