Update smac planner types

[InvincibleRMC]

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Basic Info

Info	Please fill out this column
Primary OS tested on	(Ubuntu)

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Description of contribution in a few bullet points

I saw #4916 to add ament_mypy to type check. I noticed there were some errors raised by ament_mypy so i resolved the ones in nav2_smac_planner.

Description of how this change was tested

I ran ament_mypy nav2_smac_planner/ and got no errors.

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For Maintainers:

• Check that any new parameters added are updated in docs.nav2.org
• Check that any significant change is added to the migration guide
• Check that any new features OR changes to existing behaviors are reflected in the tuning guide
• Check that any new functions have Doxygen added
• Check that any new features have test coverage
• Check that any new plugins is added to the plugins page
• If BT Node, Additionally: add to BT's XML index of nodes for groot, BT package's readme table, and BT library lists

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

see 3 files with indirect coverage changes