Make sure failsafe and surefire plugin versions match

[chingor13]

Fixes #6968

This also fixes an issue where spanner integration tests hang - likely because of a mismatch of maven surefire and failsafe plugin versions.

[codecov]

Codecov Report

Merging #7029 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #7029      +/-   ##
============================================
- Coverage     32.15%   32.14%   -0.01%     
+ Complexity     3694     3693       -1     
============================================
  Files           248      248              
  Lines         40347    40347              
  Branches       6129     6129              
============================================
- Hits          12972    12970       -2     
- Misses        26309    26310       +1     
- Partials       1066     1067       +1

Impacted Files	Coverage Δ	Complexity Δ
...oogle/cloud/spanner/jdbc/SingleUseTransaction.java	86% <0%> (-1%)	36% <0%> (-1%)

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[skuruppu]

Thanks for the fix. I confirmed by running it that it works.