fix: update SQL syntax for H2 2.x compatibility

H2 2.x (managed by Spring Boot 2.7.18) removed support for the
non-standard 'DROP TABLE <table> IF EXISTS' syntax and the SERIAL
pseudo-type. Updated to standard SQL:
- DROP TABLE IF EXISTS customers
- id INT AUTO_INCREMENT PRIMARY KEY

Co-Authored-By: Lukas Burger <lukas.burger@cognition.ai>

Author: devin-ai-integration[bot]

src/main/java/hello/Application.java

@@ -63,8 +63,8 @@ public CommandLineRunner run(RestTemplate restTemplate) throws Exception {
     public void run(String... args) throws Exception {
         log.info("Creating tables");
 
-        jdbcTemplate.execute("DROP TABLE customers IF EXISTS");
-        jdbcTemplate.execute("CREATE TABLE customers(id SERIAL, first_name VARCHAR(255), last_name VARCHAR(255))");
+        jdbcTemplate.execute("DROP TABLE IF EXISTS customers");
+        jdbcTemplate.execute("CREATE TABLE customers(id INT AUTO_INCREMENT PRIMARY KEY, first_name VARCHAR(255), last_name VARCHAR(255))");
 
         // Split up the array of whole names into an array of first/last names
         List<Object[]> splitUpNames = Arrays.asList("John Woo", "Jeff Dean", "Josh Bloch", "Josh Long")