fix(isMobilePhone): fix es-PA regex to validate only Panamanian mobile numbers

The previous regex /^(\+?507)\d{7,8}$/ was too permissive:
- Allowed any starting digit after country code (should be 6 for mobile)
- Accepted 7 or 8 digit lengths (mobile must be exactly 8 digits)
- Did not support hyphenated format (6XXX-XXXX)

The new regex /^(\+?507)6\d{3}-?\d{4}$/ enforces:
- Mobile numbers must start with 6
- Exactly 8 digits after country code
- Optional hyphen in 6XXX-XXXX format

References:
- https://en.wikipedia.org/wiki/Telephone_numbers_in_Panama
- Panamanian mobile numbers: +507 6XXX-XXXX

Fixes #2433

Author: Shrawak

src/lib/isMobilePhone.js

@@ -88,7 +88,7 @@ const phones = {
   'es-PE': /^(\+?51)?9\d{8}$/,
   'es-MX': /^(\+?52)?(1|01)?\d{10,11}$/,
   'es-NI': /^(\+?505)\d{7,8}$/,
-  'es-PA': /^(\+?507)\d{7,8}$/,
+  'es-PA': /^(\+?507)6\d{3}-?\d{4}$/,
   'es-PY': /^(\+?595|0)9[9876]\d{7}$/,
   'es-SV': /^(\+?503)?[67]\d{7}$/,
   'es-UY': /^(\+598|0)9[1-9][\d]{6}$/,

test/validators.test.js

@@ -9588,17 +9588,22 @@ describe('Validators', () => {
       {
         locale: 'es-PA',
         valid: [
-          '+5076784565',
-          '+5074321557',
-          '5073331112',
-          '+50723431212',
+          '+50761234567',
+          '+50768456789',
+          '50762345678',
+          '+5076123-4567',
+          '+50769876543',
         ],
         invalid: [
           '+50755555',
           '+207123456',
           '2001236542',
           '+507987643254',
           '+507jjjghtf',
+          '+50712345678',
+          '+5073456789',
+          '+507234312',
+          '+50751234567',
         ],
       },
       {