Update conan.yml (#469)

Author: lia-viam

.github/workflows/conan.yml

@@ -190,8 +190,9 @@ jobs:
       - name: Update CMake for bullseye
         if: ${{ matrix.image  == 'debian:bullseye' }}
         run: |
-          apt-add-repository -y 'deb http://deb.debian.org/debian bullseye-backports main'
-
+          apt-get install -y software-properties-common
+          apt-add-repository -y 'deb https://archive.debian.org/debian bullseye-backports main'
+          
           apt-get update
           apt-get -y install cmake