Add gene name to report

[timodonnell]

Adds a "gene_name" column to the first sheet of the xlsx report.

Also call close rather than save in pandas.ExcelWriter.

[coveralls]

coverage: 89.17% (-7.1%) from 96.289%
when pulling 9d0cc7f on add-gene-name-to-report
into a95e4e1 on main.