Replace import placeholder before running formatting (#1717)

Makefile

@@ -41,8 +41,8 @@ update-version:
 
 CURRENT_MAJOR_VERSION := $(shell cat VERSION | sed 's/\..*//')
 codegen-format:
+	@find . -name '*.go' -exec perl -pi -e 's|github.com/stripe/stripe-go/\[MAJOR_VERSION\]|github.com/stripe/stripe-go/v$(CURRENT_MAJOR_VERSION)|' {} +
 	go fmt ./...
 	go install golang.org/x/tools/cmd/goimports@latest && goimports -w example/generated_examples_test.go
-	@find . -name '*.go' -exec perl -pi -e 's|github.com/stripe/stripe-go/\[MAJOR_VERSION\]|github.com/stripe/stripe-go/v$(CURRENT_MAJOR_VERSION)|' {} +
 
 .PHONY: codegen-format update-version