Update type hints

[laurencap]

Issue #, if available: Closes #754

Description of changes:

Update type hints to use built-ins rather than typing. This is recommended for Python 3.9+.

This also allows us to remove a bit of code from api.py which was handling these different inputs, as AutoQASM needs to inspect type hints.

Testing done:
no new functionality, updates handled by existing tests.

Merge Checklist

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• I have read the CONTRIBUTING doc
• I used the commit message format described in CONTRIBUTING
• I have updated any necessary documentation, including READMEs and API docs (if appropriate)

Tests

• I have added tests that prove my fix is effective or that my feature works (if appropriate)
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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (f51964f) 100.00% compared to head (8bd9f7f) 100.00%.
Report is 8 commits behind head on feature/autoqasm.

❗ Current head 8bd9f7f differs from pull request most recent head 3b0683a. Consider uploading reports for the commit 3b0683a to get more accurate results

Additional details and impacted files

@@                Coverage Diff                 @@
##           feature/autoqasm      #753   +/-   ##
==================================================
  Coverage            100.00%   100.00%           
==================================================
  Files                   162       162           
  Lines                  9660      9650   -10     
  Branches               2080      2077    -3     
==================================================
- Hits                   9660      9650   -10     

Files	Coverage Δ
src/braket/experimental/autoqasm/api.py	100.00% <100.00%> (ø)
...experimental/autoqasm/instructions/instructions.py	100.00% <100.00%> (ø)
...experimental/autoqasm/instructions/measurements.py	100.00% <100.00%> (ø)
...raket/experimental/autoqasm/instructions/qubits.py	100.00% <100.00%> (ø)
...rc/braket/experimental/autoqasm/program/program.py	100.00% <100.00%> (ø)
src/braket/experimental/autoqasm/pulse/pulse.py	100.00% <100.00%> (ø)
...ket/experimental/autoqasm/transpiler/transpiler.py	100.00% <100.00%> (ø)
src/braket/experimental/autoqasm/types/types.py	100.00% <100.00%> (ø)

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