Add Protobuf dev libraries to Spot C++ SDK debian deps (#8)

Signed-off-by: Michel Hidalgo <mhidalgo@theaiinstitute.com>

Author: mhidalgo-rai

cpp/CMakeLists.txt

@@ -321,7 +321,7 @@ if (UNIX)
   set(CPACK_PACKAGE_NAME "spot-cpp-sdk")
   set(CPACK_DEBIAN_FILE_NAME DEB-DEFAULT)
   set(CPACK_DEBIAN_PACKAGE_SHLIBDEPS ON)
-  set(CPACK_DEBIAN_PACKAGE_DEPENDS "libcli11-dev (>=2.1.2), libgrpc++-dev (>=1.30.2)")  # not picked up by shlibdeps, thus listed explicitly
+  set(CPACK_DEBIAN_PACKAGE_DEPENDS "libcli11-dev (>=2.1.2), libgrpc++-dev (>=1.30.2), libprotobuf-dev (>=3.12.4)")  # not picked up by shlibdeps, thus listed explicitly
   set(CPACK_DEBIAN_PACKAGE_MAINTAINER "Boston Dynamics SDK Publisher <bd-sdk-publisher@bostondynamics.com>")
   set(CPACK_PACKAGE_VENDOR "Boston Dynamics")
   set(CPACK_PACKAGE_VERSION ${PROJECT_VERSION})