Give DrivetrainCANPosition a static length

Signed-off-by: Maxwell Henderson <mxwhenderson@gmail.com>
Change-Id: Ia18a4d37f8f157f818bb129ec6a8ef91b4e45291
diff --git a/y2024/wpilib_interface.cc b/y2024/wpilib_interface.cc
index b708266..b1675db 100644
--- a/y2024/wpilib_interface.cc
+++ b/y2024/wpilib_interface.cc
@@ -375,6 +375,8 @@
           auto drivetrain_falcon_vector =
               drivetrain_can_builder->add_talonfxs();
 
+          CHECK(drivetrain_falcon_vector->reserve(drivetrain_talonfxs.size()));
+
           for (auto talonfx : drivetrain_talonfxs) {
             talonfx->SerializePosition(
                 drivetrain_falcon_vector->emplace_back(),