change gene=* to gene_name=* in hku1/genemap.gff #2

Initially, the workflow failed with the following error:

```
Error:
   0: When reading genome annotation
   1: When reading file: "config/hku1/genemap.gff"
   2: Attempted to parse the genome annotation as JSON and as GFF, but both attempts failed:
      JSON error: invalid type: string "NC_006577.2\tfeature\tsource\t1\t29926\t.\t+\t.\tgene=nuc NC_006577.2\tfeature\tgene\t206\t13600
\t.\t+\t.\tgene=ORF1a NC_006577.2\tfeature\tgene\t13600\t21753\t.\t+\t.\tgene=ORF1b NC_006577.2\tfeature\tgene\t21773\t22933\t.\t+\t.\tg
ene=HE NC_006577.2\tfeature\tgene\t22942\t27012\t.\t+\t.\tgene=Spike NC_006577.2\tfeature\tgene\t22978\t25221\t.\t+\t.\tgene=S1 NC_00657
7.2\tfeature\tgene\t27051\t27380\t.\t+\t.\tgene=S2 NC_006577.2\tfeature\tgene\t27051\t27380\t.\t+\t.\tgene=ORF4 NC_006577.2\tfeature\tge
ne\t27373\t27621\t.\t+\t.\tgene=E NC_006577.2\tfeature\tgene\t27633\t28304\t.\t+\t.\tgene=M NC_006577.2\tfeature\tgene\t28320\t29645\t.\
t+\t.\tgene=N NC_006577.2\tfeature\tgene\t28342\t28959\t.\t+\t.\tgene=N2", expected struct GeneMap at line 2 column 1

      GFF3 error: When processing gene, 'N': When processing feature group 'N' ('N') of type 'gene': genes must consist of exactly one f
eature: Expected exactly one element, but found: 2
   2:

Location:
   /workdir/packages/nextclade/src/gene/gene_map.rs:56
```

While looking at the referenced file, and comparing it to the other
`genemap.gff` files in the config, I noticed that all the others used
`gene_name` for everything after the first `gene` line. I changed this
file to match, and the workflow got past the point where it was
previously erroring out.

I have no idea why this worked; hopefully somebody will explain in the
code review.

phylogenetic/config/hku1/genemap.gff

@@ -1,13 +1,13 @@
 ##sequence-region NC_006577.2 1 29926
 NC_006577.2	feature	source	1	29926	.	+	.	gene=nuc
-NC_006577.2	feature	gene	206	13600	.	+	.	gene=ORF1a
-NC_006577.2	feature	gene	13600	21753	.	+	.	gene=ORF1b
-NC_006577.2	feature	gene	21773	22933	.	+	.	gene=HE
-NC_006577.2	feature	gene	22942	27012	.	+	.	gene=Spike
-NC_006577.2	feature	gene	22978	25221	.	+	.	gene=S1
-NC_006577.2	feature	gene	27051	27380	.	+	.	gene=S2
-NC_006577.2	feature	gene	27051	27380	.	+	.	gene=ORF4
-NC_006577.2	feature	gene	27373	27621	.	+	.	gene=E
-NC_006577.2	feature	gene	27633	28304	.	+	.	gene=M
-NC_006577.2	feature	gene	28320	29645	.	+	.	gene=N
-NC_006577.2	feature	gene	28342	28959	.	+	.	gene=N2
+NC_006577.2	feature	gene	206	13600	.	+	.	gene_name=ORF1a
+NC_006577.2	feature	gene	13600	21753	.	+	.	gene_name=ORF1b
+NC_006577.2	feature	gene	21773	22933	.	+	.	gene_name=HE
+NC_006577.2	feature	gene	22942	27012	.	+	.	gene_name=Spike
+NC_006577.2	feature	gene	22978	25221	.	+	.	gene_name=S1
+NC_006577.2	feature	gene	27051	27380	.	+	.	gene_name=S2
+NC_006577.2	feature	gene	27051	27380	.	+	.	gene_name=ORF4
+NC_006577.2	feature	gene	27373	27621	.	+	.	gene_name=E
+NC_006577.2	feature	gene	27633	28304	.	+	.	gene_name=M
+NC_006577.2	feature	gene	28320	29645	.	+	.	gene_name=N
+NC_006577.2	feature	gene	28342	28959	.	+	.	gene_name=N2