build: fix npm version detection

Npm's package.json now contains two fields named "version".
Grep for the top-level one.

Fixes: nodejs/build#2850

PR-URL: #41575
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Vladimir de Turckheim <vlad2t@hotmail.com>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Zijian Liu <lxxyxzj@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Christian Clauss <cclauss@me.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

Makefile

@@ -830,7 +830,7 @@ PLATFORM=$(shell uname | tr '[:upper:]' '[:lower:]')
 ifeq ($(findstring os/390,$PLATFORM),os/390)
 PLATFORM ?= os390
 endif
-NPMVERSION=v$(shell cat deps/npm/package.json | grep '"version"' | sed 's/^[^:]*: "\([^"]*\)",.*/\1/')
+NPMVERSION=v$(shell cat deps/npm/package.json | grep '^  "version"' | sed 's/^[^:]*: "\([^"]*\)",.*/\1/')
 
 UNAME_M=$(shell uname -m)
 ifeq ($(findstring x86_64,$(UNAME_M)),x86_64)