Bump mold version to 0.9.1

Author: rui314

Makefile

@@ -6,7 +6,7 @@ GIT_HASH = $(shell [ -d .git ] && git rev-parse HEAD)
 
 CPPFLAGS = -g -Imimalloc/include -pthread -std=c++20 \
            -Wno-deprecated-volatile \
-           -DMOLD_VERSION=\"0.1.1\" \
+           -DMOLD_VERSION=\"0.9.1\" \
            -DGIT_HASH=\"$(GIT_HASH)\" \
 	   $(EXTRA_CPPFLAGS)
 LDFLAGS = $(EXTRA_LDFLAGS)