Fix wrong dictionary access

The dictionary is accessed, expecting a None on non-existing keys, but
mistakenly uses the `[]` bracket syntax for indexing, as opposed to `.get` which
will return `None` on non-existing keys.

Signed-off-by: Ole Petter <[email protected]>

cfbs/commands.py

@@ -309,7 +309,7 @@ def status_command() -> int:
     print("Description: %s" % config["description"])
     print("File:        %s" % cfbs_filename())
 
-    modules = config["build"]
+    modules = config.get("build")
     if not modules:
         return 0
     print("\nModules:")