Update debian distros build

.travis.yml

@@ -10,7 +10,6 @@ branches:
   only:
     - master
     - master_nc
-    - bugfix/RND-467-screenshot-ubuntu-packages-are-broken-18.04-20.04
 
 cache:
     directories:
@@ -34,34 +33,44 @@ env:
 matrix:
     include:
         - os: linux
-          # 31
+          # 1 - Fedora 31
           env: OS=fedora DIST=31 EXTEN=rpm
           services: docker
         - os: linux
-          # 32
+          # 2 - Fedora 32
           env: OS=fedora DIST=32 EXTEN=rpm
           services: docker
         - os: linux
-          # Ubuntu 16.04 LTS
+          # 3 - Ubuntu 16.04 LTS
           env: OS=ubuntu DIST=xenial EXTEN=deb
           services: docker
         - os: linux
-          # Ubuntu 18.04 LTS
+          # 4 - Ubuntu 18.04 LTS
           env: OS=ubuntu DIST=bionic EXTEN=deb
           services: docker
         - os: linux
-          # Ubuntu 20.04 LTS
+          # 5 - Ubuntu 20.04 LTS
           env: OS=ubuntu DIST=focal EXTEN=deb
           services: docker
         - os: linux
-          # 9
+          # 6 - Debian stretch
           env: OS=debian DIST=stretch EXTEN=deb
           services: docker
         - os: linux
+          # 7 - Debian 9 (stretch)
+          env: OS=debian DIST=stretch EXTEN=deb
+          services: docker
+        - os: linux
+          # 8 - Debian 10 (buster)
+          env: OS=debian DIST=buster EXTEN=deb
+          services: docker
+        - os: linux
+          # 8
           # No docker environment, just for CI build & test
           # ubuntu xenial;  default Qt version is 5.6.1
           env: OS=ubuntu DIST=xenial EXTEN=other
        - os: osx
+         # 9 - MacOS
          compiler: clang
          osx_image: xcode9.2