Argon2 the third part: borg key change-algorithm

[hexagonrecursion]

As promised I have implemented key change-algorithm.

My plan after this is merged:

• The fourth part: add an argon2 benchmark to borg benchmark cpu
• The fifth part: changelog and usage docs.

[codecov-commenter]

Codecov Report

Merging #6549 (5a31c89) into master (1e213e9) will decrease coverage by 0.00%.
The diff coverage is 75.00%.

@@            Coverage Diff             @@
##           master    #6549      +/-   ##
==========================================
- Coverage   83.08%   83.07%   -0.01%     
==========================================
  Files          39       39              
  Lines       10574    10586      +12     
  Branches     2069     2070       +1     
==========================================
+ Hits         8785     8794       +9     
- Misses       1288     1290       +2     
- Partials      501      502       +1     

Impacted Files	Coverage Δ
src/borg/archiver.py	78.41% <75.00%> (-0.02%)	⬇️

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[ThomasWaldmann]

some minor nitpicks, rest LGTM.

[ThomasWaldmann]

one last thing

[ThomasWaldmann]

btw, there is already an argon2 / kdf cpu benchmark, but it should be updated so both benchmarks use the same parameters as borg in production.

[hexagonrecursion]

one last thing

What "last thing"?

[ThomasWaldmann]

Thanks, merged!