Improve run_gurobi to wait for available token

[tgi-climact]

When using a Gurobi floating token server license or a web single-use license, a program that calls Gurobi Optimizer must obtain a token from a Gurobi token server before it can solve an optimization model. When no token is available, an exception gurobipy.GurobiError is raised (source : https://support.gurobi.com/hc/en-us/articles/360029879251-How-do-I-check-the-availability-of-floating-license-tokens).

To avoid Gurobi Optimizer throwing an error, I suggest to optionally wait for an available token. This is the purpose of this PR. The waiting time (in seconds) can be configured in the solver options.

Side note : This enables scenarios in PyPSA-Eur.

[codecov]

Codecov Report

Attention: Patch coverage is 20.00000% with 12 lines in your changes are missing coverage. Please review.

Project coverage is 86.43%. Comparing base (f0c8457) to head (6ae5bfc).

Files	Patch %	Lines
linopy/solvers.py	20.00%	10 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #281      +/-   ##
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- Coverage   89.69%   86.43%   -3.27%     
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  Files          16       16              
  Lines        4019     4032      +13     
  Branches      939      941       +2     
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- Hits         3605     3485     -120     
- Misses        281      421     +140     
+ Partials      133      126       -7     

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[FabianHofmann]

thanks @tgi-climact, perhaps 60 secs is a bit long?

[tgi-climact]

thanks @tgi-climact, perhaps 60 secs is a bit long?

Depending on the optimisation in progress, it could be very long or very short. I would like to avoid spam on the Gurobi servers. What would be your suggestion?

[FabianHofmann]

Depending on the optimisation in progress, it could be very long or very short. I would like to avoid spam on the Gurobi servers. What would be your suggestion?

okay I see, then the 60 secs make sense I guess.