Update module theckman/go-flock to v0.8.0

go.mod

@@ -19,7 +19,7 @@ require (
 	github.com/prometheus/client_golang v1.9.0
 	github.com/russross/blackfriday/v2 v2.0.1
 	github.com/shurcooL/sanitized_anchor_name v1.0.0 // indirect
-	github.com/theckman/go-flock v0.7.1
+	github.com/theckman/go-flock v0.8.0
 	github.com/tstranex/u2f v1.0.0
 	go.opencensus.io v0.22.5
 	golang.org/x/crypto v0.0.0-20201221181555-eec23a3978ad