Remove testmodule in src/modules/Makefile. (redis#9250)

src/modules make failed. As in redis#3718 testmodule.c was removed. But the makefile was not updated

(cherry picked from commit d54c908)

src/modules/Makefile

@@ -13,7 +13,7 @@ endif
 
 .SUFFIXES: .c .so .xo .o
 
-all: helloworld.so hellotype.so helloblock.so testmodule.so hellocluster.so hellotimer.so hellodict.so hellohook.so helloacl.so
+all: helloworld.so hellotype.so helloblock.so hellocluster.so hellotimer.so hellodict.so hellohook.so helloacl.so
 
 .c.xo:
 	$(CC) -I. $(CFLAGS) $(SHOBJ_CFLAGS) -fPIC -c $< -o $@
@@ -58,10 +58,5 @@ helloacl.xo: ../redismodule.h
 helloacl.so: helloacl.xo
 	$(LD) -o $@ $< $(SHOBJ_LDFLAGS) $(LIBS) -lc
 
-testmodule.xo: ../redismodule.h
-
-testmodule.so: testmodule.xo
-	$(LD) -o $@ $< $(SHOBJ_LDFLAGS) $(LIBS) -lc
-
 clean:
 	rm -rf *.xo *.so