bump: python cloudevents sdk major version 2 + related bumps

[gauron99]

• python required is not >=3.10 because of the cloudevents 2.*
• update the python cloudevents templates for compatibility with the new 2.* version
• func-python was updated and release new 0.8.0
• s2i container expected w/ 3.10+ python version as well, needed bump

[knative-prow]

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[knative-prow]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 55.65%. Comparing base (ada57d2) to head (579a1dc).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3604      +/-   ##
==========================================
- Coverage   56.26%   55.65%   -0.62%     
==========================================
  Files         180      180              
  Lines       20504    20512       +8     
==========================================
- Hits        11537    11415     -122     
- Misses       7762     7936     +174     
+ Partials     1205     1161      -44     

Flag	Coverage Δ
e2e	36.22% <100.00%> (+0.09%)	⬆️
e2e go	32.86% <0.00%> (+0.28%)	⬆️
e2e node	28.60% <0.00%> (+0.28%)	⬆️
e2e python	?
e2e quarkus	28.74% <0.00%> (+0.28%)	⬆️
e2e rust	28.15% <0.00%> (+0.27%)	⬆️
e2e springboot	28.18% <0.00%> (+1.86%)	⬆️
e2e typescript	28.71% <0.00%> (+0.28%)	⬆️
e2e-config-ci	18.08% <0.00%> (-0.01%)	⬇️
integration	17.48% <0.00%> (+0.05%)	⬆️
unit macos-14	43.34% <100.00%> (-0.03%)	⬇️
unit macos-latest	43.34% <100.00%> (-0.03%)	⬇️
unit ubuntu-24.04-arm	43.53% <100.00%> (-0.02%)	⬇️
unit ubuntu-latest	44.22% <100.00%> (-0.03%)	⬇️
unit windows-latest	43.37% <100.00%> (-0.03%)	⬇️

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[gauron99]

func-python needs update first, will update