Allow to set maximum peg in/out for mint

[sihamon]

Add parameter mint_max_peg_in and mint_max_peg_out to optionally limit peg in/out for mint. If set, these are added to /info.
Issues: closes #196

[codecov]

Codecov Report

Patch coverage: 18.75% and project coverage change: -0.05 ⚠️

Comparison is base (4088ab2) 56.94% compared to head (7022d28) 56.90%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #209      +/-   ##
==========================================
- Coverage   56.94%   56.90%   -0.05%     
==========================================
  Files          41       41              
  Lines        3159     3288     +129     
==========================================
+ Hits         1799     1871      +72     
- Misses       1360     1417      +57     

Impacted Files	Coverage Δ
cashu/mint/ledger.py	31.41% <0.00%> (-0.66%)	⬇️
cashu/mint/router.py	0.00% <0.00%> (ø)
cashu/core/base.py	95.07% <100.00%> (+0.02%)	⬆️
cashu/core/settings.py	97.33% <100.00%> (+0.07%)	⬆️

... and 3 files with indirect coverage changes

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