Change type declaration of addCustomField type to allow integer and f…

…loat values (#451)

src/Issue/IssueField.php

@@ -150,7 +150,7 @@ public function getCustomFields(): ?array
         return $this->customFields;
     }
 
-    public function addCustomField(string $key, string $value): static
+    public function addCustomField(string $key, string|int|float $value): static
     {
         $this->customFields[$key] = $value;