Put open mocks in try catch

[snuyanzin]

The PR makes open mocks in autoclosable, removes usage of deprecated Faker#instance and fix some warnings about assertJ methods

[codecov-commenter]

Codecov Report

Merging #366 (d7a2168) into main (2c1a3f3) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##               main     #366      +/-   ##
============================================
- Coverage     94.67%   94.65%   -0.03%     
+ Complexity     1945     1943       -2     
============================================
  Files           205      205              
  Lines          3889     3888       -1     
  Branches        385      385              
============================================
- Hits           3682     3680       -2     
+ Misses          108      107       -1     
- Partials         99      101       +2     

Impacted Files	Coverage Δ
.../java/net/datafaker/service/FakeValuesService.java	87.31% <100.00%> (-0.03%)	⬇️
src/main/java/net/datafaker/Faker.java	88.75% <0.00%> (-5.00%)	⬇️
.../main/java/net/datafaker/service/FakerContext.java	86.84% <0.00%> (+2.63%)	⬆️
...ker/idnumbers/pt/br/IdNumberGeneratorPtBrUtil.java	96.29% <0.00%> (+3.70%)	⬆️

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