Add public_url validation to JC instance_url

app/models/jira_connect_installation.rb

@@ -11,6 +11,7 @@ class JiraConnectInstallation < ApplicationRecord
   validates :client_key, presence: true, uniqueness: true
   validates :shared_secret, presence: true
   validates :base_url, presence: true, public_url: true
+  validates :instance_url, public_url: true, allow_blank: true
 
   scope :for_project, -> (project) {
     distinct

spec/models/jira_connect_installation_spec.rb

@@ -15,6 +15,9 @@
 
     it { is_expected.to allow_value('https://test.atlassian.net').for(:base_url) }
     it { is_expected.not_to allow_value('not/a/url').for(:base_url) }
+
+    it { is_expected.to allow_value('https://test.atlassian.net').for(:instance_url) }
+    it { is_expected.not_to allow_value('not/a/url').for(:instance_url) }
   end
 
   describe '.for_project' do