Ensure pygrb webpage is generated after all results files are produced

[pannarale]

PyGRB webpages often had gaps that could be fixed by running the pycbc_make_html_page job by hand, after a full workflow was completed. This was a sign of incorrect dependencies in the workflow (i.e., pycbc_make_html_page was being called too early).

To fix this, this PR simply moves the call to make_results_web_page further down in the pycbc_pygrb_results_workflow workflow generator, so that the job dependencies are correct: all nodes that will give jobs that produce plots, tables, etc. are now in the collection of dependencies passed to make_results_web_page, so pycbc_make_html_page runs after those jobs.

This is a: bug fix.

This change affects: PyGRB

I produced this results webpage from a short workflow with no need to "sync" it by hand after the workflow had finished running.

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[sebastiangomezlopez]

These changes look good to me.