package/grpc: bump to version 1.37.1

Fixes from Changelog [0]:
 - Fix #25897 to avoid crashes when certificates are not yet updated
 - [Backport] Fix use-after-unref bug in fault_injection_filter.

[0] https://github.com/grpc/grpc/releases/tag/v1.37.1



Signed-off-by: Michael Nosthoff <buildroot@heine.tech>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>