[pt-model-zoo] Make PtBertQATranslator compatible with huggingface model

[frankfliu]

Change-Id: I16ce250daea8cf2a07a39b064cff9f9bfa58399d

Description

Brief description of what this PR is about

• If this change is a backward incompatible change, why must this change be made?
• Interesting edge cases to note here

[codecov-commenter]

Codecov Report

Merging #1827 (833bb1b) into master (bb5073f) will decrease coverage by 2.42%.
The diff coverage is 65.02%.

@@             Coverage Diff              @@
##             master    #1827      +/-   ##
============================================
- Coverage     72.08%   69.66%   -2.43%     
- Complexity     5126     5502     +376     
============================================
  Files           473      524      +51     
  Lines         21970    24341    +2371     
  Branches       2351     2652     +301     
============================================
+ Hits          15838    16956    +1118     
- Misses         4925     6075    +1150     
- Partials       1207     1310     +103     

Impacted Files	Coverage Δ
api/src/main/java/ai/djl/modality/cv/Image.java	69.23% <ø> (-4.11%)	⬇️
...rc/main/java/ai/djl/modality/cv/MultiBoxPrior.java	76.00% <ø> (ø)
...rc/main/java/ai/djl/modality/cv/output/Joints.java	71.42% <ø> (ø)
.../main/java/ai/djl/modality/cv/output/Landmark.java	100.00% <ø> (ø)
...main/java/ai/djl/modality/cv/output/Rectangle.java	72.41% <0.00%> (ø)
...i/djl/modality/cv/translator/BigGANTranslator.java	21.42% <0.00%> (-5.24%)	⬇️
...odality/cv/translator/BigGANTranslatorFactory.java	33.33% <0.00%> (+8.33%)	⬆️
...nslator/InstanceSegmentationTranslatorFactory.java	14.28% <0.00%> (-3.90%)	⬇️
.../cv/translator/SemanticSegmentationTranslator.java	0.00% <0.00%> (ø)
.../cv/translator/StyleTransferTranslatorFactory.java	40.00% <ø> (ø)
... and 418 more

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