fix: use glob for parse_kraken2_reads output to avoid interpolation issues

The output declaration File read_taxonomy = "~{out_compressed}" was failing
to register on some backends. Switch to glob("*.read_taxonomy.tsv.zst")[0]
which finds the file regardless of how interpolation evaluates.

Author: carze

pipes/WDL/tasks/tasks_metagenomics.wdl

@@ -2189,7 +2189,7 @@ task parse_kraken2_reads {
   >>>
 
   output {
-    File read_taxonomy = "~{out_compressed}"
+    File read_taxonomy = glob("*.read_taxonomy.tsv.zst")[0]
   }
 
   runtime {