Remove comma to make the package build.

[wilcobonestroo]

---

Basic Info

Info	Please fill out this column
Ticket(s) this addresses	(PR2884)
Primary OS tested on	(Ubuntu)

---

Description of contribution in a few bullet points

• Fix a typo to make the nav2_costmap_2d package compile again.

[mergify]

@wilcobonestroo, please properly fill in PR template in the future. @SteveMacenski, use this instead.

• Check that any new parameters added are updated in navigation.ros.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

[wilcobonestroo]

@SteveMacenski already fixed it in #2886