build(makefile): drop -RC1 suffix from default TAG

Author: pierre275

Makefile

@@ -1,6 +1,6 @@
 __PHONY__: build build-deps build-deps-core build-deps-horizon
 
-TAG?=organization-mainnet-v1.0-p23.0.1-RC1
+TAG?=organization-mainnet-v1.0-p23.0.1
 CORE_REPO?=https://github.com/stellar/stellar-core.git
 CORE_REF?=v23.0.1
 CORE_CONFIGURE_FLAGS?=--disable-tests