buildman.yml: fixed installation manpage job

Author: firewave

.github/workflows/buildman.yml

@@ -44,7 +44,6 @@ jobs:
       - uses: actions/checkout@v3
 
       - name: Install missing software on ubuntu
-        if: contains(matrix.image, 'ubuntu')
         run: |
           apt-get update
           apt-get install -y xsltproc docbook-xsl