Update Guam timezone to Pacific/Guam (#51)

To match the IANA timezone registry, this updates the timezone listed
for Guam to `Pacific/Guam` from `Chamorro/Guam`.

Reference: https://data.iana.org/time-zones/tzdb-2025a/zone1970.tab

Author: dugancathal

lib/data/US.yml

@@ -48136,67 +48136,67 @@
   :state_code: GU
   :state_name: Guam
   :city: Hagatna
-  :time_zone: Chamorro/Guam
+  :time_zone: Pacific/Guam
 '96912':
   :state_code: GU
   :state_name: Guam
   :city: Dededo
-  :time_zone: Chamorro/Guam
+  :time_zone: Pacific/Guam
 '96913':
   :state_code: GU
   :state_name: Guam
   :city: Barrigada
-  :time_zone: Chamorro/Guam
+  :time_zone: Pacific/Guam
 '96915':
   :state_code: GU
   :state_name: Guam
   :city: Santa
-  :time_zone: Chamorro/Guam
+  :time_zone: Pacific/Guam
 '96916':
   :state_code: GU
   :state_name: Guam
   :city: Merizo
-  :time_zone: Chamorro/Guam
+  :time_zone: Pacific/Guam
 '96917':
   :state_code: GU
   :state_name: Guam
   :city: Inarajan
-  :time_zone: Chamorro/Guam
+  :time_zone: Pacific/Guam
 '96919':
   :state_code: GU
   :state_name: Guam
   :city: Agana
-  :time_zone: Chamorro/Guam
+  :time_zone: Pacific/Guam
 '96921':
   :state_code: GU
   :state_name: Guam
   :city: Barrigada
-  :time_zone: Chamorro/Guam
+  :time_zone: Pacific/Guam
 '96923':
   :state_code: GU
   :state_name: Guam
   :city: Mangilao
-  :time_zone: Chamorro/Guam
+  :time_zone: Pacific/Guam
 '96928':
   :state_code: GU
   :state_name: Guam
   :city: Agat
-  :time_zone: Chamorro/Guam
+  :time_zone: Pacific/Guam
 '96929':
   :state_code: GU
   :state_name: Guam
   :city: Yigo
-  :time_zone: Chamorro/Guam
+  :time_zone: Pacific/Guam
 '96931':
   :state_code: GU
   :state_name: Guam
   :city: Tamuning
-  :time_zone: Chamorro/Guam
+  :time_zone: Pacific/Guam
 '96932':
   :state_code: GU
   :state_name: Guam
   :city: Hagatna
-  :time_zone: Chamorro/Guam
+  :time_zone: Pacific/Guam
 '96704':
   :state_code: HI
   :state_name: Hawaii