Added: migrations for not null columns and delete password field.

src/main/resources/db/migration/V1_0_1__AlterUser.sql

@@ -0,0 +1,5 @@
+ALTER TABLE "users"
+  ALTER COLUMN username SET NOT NULL,
+  ALTER COLUMN "firstName" SET NOT NULL,
+  ALTER COLUMN "lastName" SET NOT NULL,
+  ALTER COLUMN "email" SET NOT NULL;

src/main/resources/db/migration/V1_0_2__DeletePassword.sql

@@ -0,0 +1,2 @@
+ALTER TABLE "users"
+    DROP COLUMN "hashed_password";