manifest: Update nRF hw models to latest

Update the HW models module to:
968d55ff22579080466bf2f482596dd6e35361c6

Including the following:
968d55f 54LM20: Also build CRACEN RNG
2c6d49d CRACEN RNG: Add model of the new version of the IP
914b475 54LM20: Add first version
fb68cc6 grtc hal replacement: Remove pointless macro use
ef2f63e Fix wrong NRF_UARTE register reference
63a2e85 README: Clarify the models are not perfect, and correct links

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

Author: aescolar

west.yml

@@ -325,7 +325,7 @@ manifest:
       groups:
         - tools
     - name: nrf_hw_models
-      revision: 9eb489fdcde23d4f69ded78bca872bfc31b5ee79
+      revision: 968d55ff22579080466bf2f482596dd6e35361c6
       path: modules/bsim_hw_models/nrf_hw_models
     - name: nrf_wifi
       revision: 294314b8622bfa582f43b229504d42201e1a3443