travis-ci: bumped OpenSSL to 1.1.1g.

This version contains a high-severity bugfix:
https://www.openssl.org/news/secadv/20200421.txt

Author: spacewander

.travis.yml

@@ -49,7 +49,7 @@ env:
   jobs:
     - NGINX_VERSION=1.17.8 OPENSSL_VER=1.0.2u OPENSSL_PATCH_VER=1.0.2h
     - NGINX_VERSION=1.17.8 OPENSSL_VER=1.1.0l OPENSSL_PATCH_VER=1.1.0d
-    - NGINX_VERSION=1.17.8 OPENSSL_VER=1.1.1f OPENSSL_PATCH_VER=1.1.1f
+    - NGINX_VERSION=1.17.8 OPENSSL_VER=1.1.1g OPENSSL_PATCH_VER=1.1.1f
 
 services:
  - memcached