Update drug detection for new Guide to Pharmacology prefixes

[dustine32]

Some drug reactions were being let through (not filtered out) in the conversion code because the expected xref prefix of certain drug entities began being output in the upstream BioPAX as "Guide to Pharmacology - Ligands," which doesn't exactly match the expected drug prefix "Guide to Pharmacology."

pathways2GO/exchange/src/main/java/org/geneontology/gocam/exchange/PhysicalEntityOntologyBuilder.java

Line 1020 in 4080dbc

Set<String> drugDbs = new HashSet<>(Arrays.asList("IUPHAR", "Guide to Pharmacology"));

Update the code to look for prefix (instead of exact match) "Guide to Pharmacology". Example pathways are:
R-HSA-196791
R-HSA-73817
R-HSA-75105