Remove pytest installation from CI script (added to docker image)

.gitlab-ci.yml

@@ -22,7 +22,6 @@ stages:
     image: mroynard/ubuntu-toolset:stable
     script:
         - set -e
-        - pip install pytest
         - conan create
               --build missing
               -pr $CONAN_PROFILE
@@ -87,7 +86,6 @@ distcheck-package-linux-bintray:
     image: mroynard/ubuntu-toolset:stable
     script:
         - set -e
-        - pip install pytest
         - conan remote add $CONAN_BINTRAY_REMOTE_NAME $CONAN_BINTRAY_REMOTE_URL
         - conan user
                -p $CONAN_BINTRAY_API_KEY
@@ -108,7 +106,6 @@ distcheck-package-linux-lrde:
     image: mroynard/ubuntu-toolset:stable
     script:
         - set -e
-        - pip install pytest
         - conan remote add $CONAN_LRDE_REMOTE_NAME $CONAN_LRDE_REMOTE_URL
         - conan user
                -p $CONAN_LRDE_API_KEY