New install method for gxz

Signed-off-by: jolheiser <john.olheiser@gmail.com>

Makefile

@@ -78,6 +78,6 @@ release-check:
 .PHONY: release-compress
 release-compress:
 	@hash gxz > /dev/null 2>&1; if [ $$? -ne 0 ]; then \
-		$(GO) get -u github.com/ulikunitz/xz/cmd/gxz; \
+		$(GO) install github.com/ulikunitz/xz/cmd/gxz@latest; \
 	fi
 	cd $(DIST)/release/; for file in `find . -type f -name "*"`; do echo "compressing $${file}" && gxz -k -9 $${file}; done;