fix meger develop branch

db/migrate/20210609072904_add_timestamp_to_applied_projects.rb

@@ -0,0 +1,5 @@
+class AddTimestampToAppliedProjects < ActiveRecord::Migration[5.2]
+  def change
+    add_timestamps(:applied_projects, null: true)
+  end
+end

db/migrate/20210615063727_add_invite_code_index_to_projects.rb

@@ -0,0 +1,8 @@
+class AddInviteCodeIndexToProjects < ActiveRecord::Migration[5.2]
+  def change
+    add_index :projects, :invite_code
+    execute <<-SQL
+      ALTER TABLE projects MODIFY COLUMN invite_code VARCHAR(255) BINARY CHARACTER SET utf8 COLLATE utf8_bin DEFAULT NULL;
+    SQL
+  end
+end