Make the make build depends on npm_licenses task (#7843)

Signed-off-by: Luke Chen <showuon@gmail.com>

.promu.yml

@@ -18,6 +18,8 @@ build:
         -X github.com/prometheus/common/version.BuildUser={{user}}@{{host}}
         -X github.com/prometheus/common/version.BuildDate={{date "20060102-15:04:05"}}
 tarball:
+    # Whenever there are new files to include in the tarball,
+    # remember to make sure the new files will be generated after `make build`.
     files:
         - consoles
         - console_libraries

Makefile

@@ -101,7 +101,7 @@ plugins/plugins.go: plugins.yml plugins/generate.go
 plugins: plugins/plugins.go
 
 .PHONY: build
-build: assets assets-compress common-build plugins
+build: assets npm_licenses assets-compress common-build plugins
 
 .PHONY: bench_tsdb
 bench_tsdb: $(PROMU)