[#6] Makefile: Remove fmt rule, use fumpt rule instead

There were several problems:
- `fmt` was a duplicate of `fumpt`
- `fmt` used globally installed `gofumpt`

Signed-off-by: Aleksey Savchuk <a.savchuk@yadro.com>

Makefile

@@ -24,12 +24,7 @@ GOFUMPT_DIR ?= $(abspath $(BIN))/gofumpt
 GOFUMPT_VERSION_DIR ?= $(GOFUMPT_DIR)/$(GOFUMPT_VERSION)
 
 # Run all code formatters
-fmts: fmt imports
-
-# Reformat code
-fmt:
-	@echo "⇒ Processing gofmt check"
-	@gofumpt -s -w .
+fmts: fumpt imports
 
 # Reformat imports
 imports: