Install libgnutls within the CI flow (#315)

* Install libgnutls within the CI flow

* Installing gnutls only on ubuntu

* Simplify SSL priorities list string in test

Author: etr

.github/workflows/verify-build.yml

@@ -375,6 +375,11 @@ jobs:
         sudo apt-get install cppcheck ;
       if: ${{ matrix.os-type == 'ubuntu' }}
 
+    - name: Setup gnutls dependency (only on linux)
+      run: |
+        sudo apt-get install libgnutls28-dev ;
+      if: ${{ matrix.os-type == 'ubuntu' }}
+
     - name: Fetch libmicrohttpd from cache
       id: cache-libmicrohttpd
       uses: actions/cache@v2

test/integ/ws_start_stop.cpp

@@ -445,7 +445,7 @@ LT_BEGIN_AUTO_TEST(ws_start_stop_suite, ssl_with_protocol_priorities)
         .use_ssl()
         .https_mem_key("key.pem")
         .https_mem_cert("cert.pem")
-        .https_priorities("NONE:+VERS-TLS1.0:+AES-128-CBC:+SHA1:+RSA:+COMP-NULL");
+        .https_priorities("NONE:+AES-256-GCM:+SHA384");
 
     ok_resource ok;
     ws.register_resource("base", &ok);