CI: Pinning graphviz (#2630)
CI: Pinning graphviz (#2630)


cpcloud/ibis,cpcloud/ibis,cloudera/ibis,ibis-project/ibis,cloudera/ibis,cloudera/ibis,ibis-project/ibis,ibis-project/ibis,cpcloud/ibis,ibis-project/ibis,cpcloud/ibis