Makefile: use go install in the build target (cosmos#7248)

go install also caches dependency packages and
it's faster than go build.

Co-authored-by: Alessio Treglia <alessio@tendermint.com>

Makefile

@@ -84,7 +84,7 @@ include contrib/devtools/Makefile
 ###############################################################################
 
 build: go.sum
-	go build -mod=readonly ./...
+	go install -mod=readonly ./...
 
 build-simd: go.sum
 	mkdir -p $(BUILDDIR)