Handle canceled / forfeited games

[lorenzodb1]

_concat would throw an error when analysing Tottenham-Rennes, as the game was forfeited and, therefore, there is no match data available for it. The dataframe resulting from this page had fewer columns than the ones for other games in the competition, thus throwing an error.

This is a new attempt to solve #304.

[lorenzodb1]

@probberechts please let me know if these changes sit well with you. I'm open to any feedback so we can fix this issue once and for all

[codecov-commenter]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.15% 🎉

Comparison is base (d5043e6) 61.28% compared to head (7aa1446) 61.43%.
Report is 1 commits behind head on master.

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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #309      +/-   ##
==========================================
+ Coverage   61.28%   61.43%   +0.15%     
==========================================
  Files          10       10              
  Lines        1431     1434       +3     
  Branches      290      292       +2     
==========================================
+ Hits          877      881       +4     
  Misses        508      508              
+ Partials       46       45       -1     

Files Changed	Coverage Δ
soccerdata/fbref.py	86.25% <100.00%> (+0.31%)	⬆️

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