build: add submodule update to master command

Author: thunderbiscuit

justfile

@@ -28,6 +28,14 @@ submodule-init:
 submodule-reset:
   git submodule update --force
 
+[group("Submodule")]
+[doc("Checkout the bdk-ffi submodule to the latest commit on master.")]
+submodule-to-master:
+  cd ./bdk-ffi/
+  git fetch origin
+  git checkout master
+  git pull origin master
+
 [group("Build")]
 [doc("Build the library for given ARCH.")]
 build ARCH="macos-aarch64":