Lua: Fix qbs build

Amends eec48b8f8e.

Change-Id: I0328f44a6cd33116f5ac51f8127519bf734b1879
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>

src/plugins/lua/lua.qbs

@@ -34,6 +34,7 @@ QtcPlugin {
             "fetch.cpp",
             "hook.cpp",
             "inheritance.h",
+            "install.cpp",
             "layout.cpp",
             "messagemanager.cpp",
             "qtcprocess.cpp",
@@ -56,6 +57,7 @@ QtcPlugin {
             "async.lua",
             "core.lua",
             "fetch.lua",
+            "install.lua",
             "layout.lua",
             "lsp.lua",
             "messagemanager.lua",