[GNC] F::Q XAU & XAG quotes not retrieving for 2 years

[Ken Farley]

Yahoo seems to use "GC=F" as the symbol for Gold. I am able to get the 
price of gold as shown in the following output from gnc-fq-dump

--> gnc-fq-dump yahoo_json GC=F

Finance::Quote fields Gnucash uses:
     symbol: GC=F                 <=== required
       date: 10/04/2023           <=== recommended
   currency: USD                  <=== required
       last: 1837.3               <=\
        nav:                      <=== one of these
      price:                      <=/
   timezone:                      <=== optional


In a similar fashion, silver is apparently "SI=F".

--> gnc-fq-dump yahoo_json SI=F

Finance::Quote fields Gnucash uses:
     symbol: SI=F                 <=== required
       date: 10/04/2023           <=== recommended
   currency: USD                  <=== required
       last: 21.19                <=\
        nav:                      <=== one of these
      price:                      <=/
   timezone:                      <=== optional