Add types for method parameters

[stof]

Now that the Mink DriverInterface has parameter types (thanks to https://github.com/minkphp/Mink/pull/856), we can add them in the child class.

[codecov[bot]]

Codecov Report

Merging #171 (44110c8) into master (55d0474) will not change coverage. The diff coverage is 100.00%.

@@            Coverage Diff            @@
##             master     #171   +/-   ##
=========================================
  Coverage     98.00%   98.00%           
- Complexity      125      126    +1     
=========================================
  Files             1        1           
  Lines           301      301           
=========================================
  Hits            295      295           
  Misses            6        6           

Impacted Files	Coverage Δ
src/BrowserKitDriver.php	98.00% <100.00%> (ø)

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