CDRIVER-3594 build Sphinx docs without parallelism
CDRIVER-3594 build Sphinx docs without parallelism

jmikola/mongo-c-driver,beingmeta/mongo-c-driver,beingmeta/mongo-c-driver,rcsanchez97/mongo-c-driver,rcsanchez97/mongo-c-driver,mongodb/mongo-c-driver,beingmeta/mongo-c-driver,rcsanchez97/mongo-c-driver,jmikola/mongo-c-driver,rcsanchez97/mongo-c-driver,mongodb/mongo-c-driver,mongodb/mongo-c-driver,mongodb/mongo-c-driver,jmikola/mongo-c-driver,beingmeta/mongo-c-driver,beingmeta/mongo-c-driver,jmikola/mongo-c-driver,rcsanchez97/mongo-c-driver,mongodb/mongo-c-driver,rcsanchez97/mongo-c-driver,mongodb/mongo-c-driver,beingmeta/mongo-c-driver,jmikola/mongo-c-driver,rcsanchez97/mongo-c-driver,beingmeta/mongo-c-driver,jmikola/mongo-c-driver,beingmeta/mongo-c-driver,mongodb/mongo-c-driver,jmikola/mongo-c-driver