fix(dram): pass boolean string to FORMAT_KEGG_DB skip_gene_ko_link

The companion fix for the bash condition in format_kegg_db.nf requires
that skip_gene_ko_link be the string "true" or "false" rather than the
integer 1 or 0.

In bash:
  `if [ "0" ]`   -> true  (non-empty string)
  `if [ "false" ]` -> true  (still non-empty - also wrong)

The correct pattern used in format_kegg_db.nf is:
  `if [ "${skip_gene_ko_link}" = "true" ]`

which requires this value to be exactly the string "true" or "false".
Changed `params.skip_gene_ko_link ? 1 : 0` to
`params.skip_gene_ko_link ? "true" : "false"`.

Author: ruben1294

workflows/dram.nf

@@ -203,7 +203,7 @@ workflow DRAM {
 
         gene_ko_link_f = params.gene_ko_link_loc && file(params.gene_ko_link_loc).exists() ? file(params.gene_ko_link_loc) : default_sheet
         kegg_download_date = params.kegg_download_date ? params.kegg_download_date : "''"
-        skip_gene_ko_link = params.skip_gene_ko_link ? 1 : 0
+        skip_gene_ko_link = params.skip_gene_ko_link ? "true" : "false"
         FORMAT_KEGG_DB( kegg_pep_f, gene_ko_link_f, kegg_download_date, skip_gene_ko_link )
 
     } else if (params.merge_annotations){