chore(release): v1.21.0 (#708)

Author: thesyncim

Makefile

@@ -7,7 +7,7 @@ MAKEFLAGS += --no-builtin-rules
 MAKEFLAGS += -j$(NPROCS)
 
 CURRENT_VERSION_MAJOR = 1
-CURRENT_VERSION_MINOR = 20
+CURRENT_VERSION_MINOR = 21
 CURRENT_VERSION_BUG = 0
 
 GIT_DESCRIBE := $(shell git describe)