travis-ci: bumped the NGINX core to 1.19.9, remove clang compiler mod…

…e from travis to save credits. (#101)

.travis.yml

@@ -7,7 +7,6 @@ language: c
 
 compiler:
   - gcc
-  - clang
 
 env:
   global:
@@ -16,8 +15,8 @@ env:
     - LUAJIT_INC=$LUAJIT_PREFIX/include/luajit-2.1
     - LD_LIBRARY_PATH=$LUAJIT_LIB:$LD_LIBRARY_PATH
   matrix:
-    - NGINX_VERSION=1.9.15
-    - NGINX_VERSION=1.19.3
+    - NGINX_VERSION=1.17.8
+    - NGINX_VERSION=1.19.9
 
 before_install:
   - sudo apt-get install -qq -y cpanminus libgd-dev