docs: update the latest release to v1.21.0

Author: jirfag

README.md

@@ -71,19 +71,19 @@ use deprecated option `--enable-all` and a new linter is added or even without `
 It's highly recommended to install a fixed version of golangci-lint.
 Releases are available on the [releases page](https://github.com/golangci/golangci-lint/releases).
 
-Latest version: [v1.20.0](https://github.com/golangci/golangci-lint/releases/tag/v1.20.0)
+Latest version: [v1.21.0](https://github.com/golangci/golangci-lint/releases/tag/v1.21.0)
 
 Here is the recommended way to install golangci-lint:
 
 ```bash
 # binary will be $(go env GOPATH)/bin/golangci-lint
-curl -sfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh| sh -s -- -b $(go env GOPATH)/bin v1.20.0
+curl -sfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh| sh -s -- -b $(go env GOPATH)/bin v1.21.0
 
 # or install it into ./bin/
-curl -sfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh| sh -s v1.20.0
+curl -sfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh| sh -s v1.21.0
 
 # In alpine linux (as it does not come with curl by default)
-wget -O - -q https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh| sh -s v1.20.0
+wget -O - -q https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh| sh -s v1.21.0
 
 golangci-lint --version
 ```
@@ -104,7 +104,7 @@ brew upgrade golangci/tap/golangci-lint
 ### By Docker
 
 ```bash
-docker run --rm -v $(pwd):/app -w /app golangci/golangci-lint:v1.20.0 golangci-lint run -v
+docker run --rm -v $(pwd):/app -w /app golangci/golangci-lint:v1.21.0 golangci-lint run -v
 ```
 
 ### go get

scripts/gen_readme/main.go

@@ -43,6 +43,10 @@ func genReadme(tmplPath, outPath string) error {
 }
 
 func getLatestVersion() (string, error) {
+	if gitTag := os.Getenv("GIT_TAG"); gitTag != "" {
+		return gitTag, nil
+	}
+
 	out, err := exec.Command("git", "tag", "-l", "--sort=-v:refname").Output()
 	if err != nil {
 		return "", fmt.Errorf("failed to run git tag: %s", err)