manifest: Update bsim to version v2.7

Main changes since v2.6:
* ext_2G4_phy_v1: Runtime performance optimizations
* ext_2G4_libPhyComv1: Add BT LE HDT support
* ext_2G4_channel_Indoorv1: Add BT LE HDT support

Note: Like before, bsim remains fully backwards compatible

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>