Update SpotBugs to 3.1.12

[h3xstream]

Update SpotBugs to 3.1.12 which include ASM library compatible with Java 11. Fix #512

[codecov]

Codecov Report

Merging #513 into master will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #513   +/-   ##
=========================================
  Coverage     83.94%   83.94%           
  Complexity     1808     1808           
=========================================
  Files           150      150           
  Lines          4970     4970           
  Branches       1103     1103           
=========================================
  Hits           4172     4172           
  Misses          374      374           
  Partials        424      424

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