tests: upgrade openssl to 1.1.1s. (#303)

Author: zhuizhuhaomeng

.travis.yml

@@ -40,7 +40,7 @@ env:
  - TEST_NGINX_SLEEP=0.006
  matrix:
  - NGINX_VERSION=1.21.4 OPENSSL_VER=1.1.0l
- - NGINX_VERSION=1.21.4 OPENSSL_VER=1.1.1p
+ - NGINX_VERSION=1.21.4 OPENSSL_VER=1.1.1s
 
 services:
  - memcache