Add ERC165 to the SBT contract

[Hrom131]

• Since this PR suggests a bug fix, the tests have been added and the coverage is 100%.
• Since this PR introduces a new feature, the update has been discussed in an Issue or with the team.
• This PR is just a minor change, like a typo fix.

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[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (abb78ee) 100.00% compared to head (2d37c63) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##            master       #69   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           38        38           
  Lines         1482      1487    +5     
  Branches       193       196    +3     
=========================================
+ Hits          1482      1487    +5     

Files	Coverage Δ
contracts/tokens/SBT.sol	100.00% <100.00%> (ø)

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[Arvolear]

LGTM!