[M56]Update iOS pods to 6.8.1, crashlytics to 3.14.0

Note: This is updating to iOS M55 release, we might do another update if iOS M56 comes in before our release cut.

Runs from following commands:
firebase/app/client/cpp/ios/get_pods.py
firebase/app/client/cpp/ios/gen_build.sh -f 6.8.1 -c 3.14.0

PiperOrigin-RevId: 269693056

Author: cynthiajiang

version.sh

@@ -18,9 +18,9 @@
 
 # Used to generate Pod dependencies in the Firebase Unity plugin.
 declare -A POD_SDK_VERSIONS=(
-  ["released"]="6.7.0"  # gen_build.sh: [FIR] Managed by a script. DO NOT EDIT.
-  ["stable"]="6.7.0"  # gen_build.sh: [FIR] Managed by a script. DO NOT EDIT.
-  ["head"]="6.7.0"  # gen_build.sh: [FIR] Managed by a script. DO NOT EDIT.
+  ["released"]="6.8.1"  # gen_build.sh: [FIR] Managed by a script. DO NOT EDIT.
+  ["stable"]="6.8.1"  # gen_build.sh: [FIR] Managed by a script. DO NOT EDIT.
+  ["head"]="6.8.1"  # gen_build.sh: [FIR] Managed by a script. DO NOT EDIT.
 )
 
 help() {