meson: Add boost to the dependencies

Since the project uses boost library add it to meson dependencies.

Tested:
Local build no longer fails with a missing boost headers message on the
system without boost, but fails at the "meson setup build" stage with
an appropriate message.

Change-Id: I165fb61cf72adadbb1f67d64e378f84b0256307f
Signed-off-by: Konstantin Aladyshev <aladyshev22@gmail.com>
diff --git a/meson.build b/meson.build
index 4331dcf..194c69b 100644
--- a/meson.build
+++ b/meson.build
@@ -103,6 +103,8 @@
 
 configure_file(output: 'config.h', configuration: conf)
 
+boost_dep = dependency('boost')
+
 sdbusplus_dep = dependency('sdbusplus')
 sdbusplusplus_prog = find_program('sdbus++', native: true)
 sdbuspp_gen_meson_prog = find_program('sdbus++-gen-meson', native: true)
@@ -250,7 +252,7 @@
 executable(
     'phosphor-image-updater',
     image_updater_sources,
-    dependencies: [deps, ssl],
+    dependencies: [deps, ssl, boost_dep],
     install: true
 )