bump to 1.21

Author: alexferl

.github/workflows/workflow.yaml

@@ -11,7 +11,7 @@ jobs:
           fetch-depth: 2
       - uses: actions/setup-go@v2
         with:
-          go-version: '1.19'
+          go-version: '1.21'
       - name: Run coverage
         run: go test -race -coverprofile=coverage.out -covermode=atomic
       - name: Upload coverage to Codecov

go.mod

@@ -1,6 +1,6 @@
 module github.com/alexferl/echo-openapi
 
-go 1.19
+go 1.21
 
 require (
 	github.com/getkin/kin-openapi v0.123.0