Add OSS Fuzz badge

Author: antonmedv

README.md

@@ -2,6 +2,7 @@
 [![test](https://github.com/antonmedv/expr/actions/workflows/test.yml/badge.svg)](https://github.com/antonmedv/expr/actions/workflows/test.yml) 
 [![Go Report Card](https://goreportcard.com/badge/github.com/antonmedv/expr)](https://goreportcard.com/report/github.com/antonmedv/expr) 
 [![GoDoc](https://godoc.org/github.com/antonmedv/expr?status.svg)](https://godoc.org/github.com/antonmedv/expr)
+[![Fuzzing Status](https://oss-fuzz-build-logs.storage.googleapis.com/badges/expr.svg)](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=1&q=proj:expr)
 
 **Expr** is a Go-centric expression language designed to deliver dynamic configurations with unparalleled accuracy, safety, and speed.