[FotMob] Get correct team match stats using 'opponent_stats' parameter

[marcjbaron]

This fixes the issue brought up in #528 where the opponent_stats=True parameter setting returned only the opponent stats, but incorrectly labelled as the requested team's stats. When opponent_stats=True, the correctly labelled match stats for both teams should now be returned.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes are missing coverage. Please review.

Project coverage is 63.66%. Comparing base (69fb0de) to head (e75273a). Report is 50 commits behind head on master.

Files	Patch %	Lines
soccerdata/fotmob.py	0.00%	3 Missing :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #541 +/- ## ========================================== + Coverage 59.33% 63.66% +4.32% ========================================== Files 11 12 +1 Lines 1633 1910 +277 Branches 336 386 +50 ========================================== + Hits 969 1216 +247 - Misses 610 629 +19 - Partials 54 65 +11 ```

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