Connection leak when using jOOQ and spring.jooq.sql-dialect has not been set

[skcskitano]

SqlDialectLookup in jOOQ auto configuration doesn't close connection properly after obtaining it.

java.lang.Exception: Apparent connection leak detected
    at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:128)
    at org.springframework.boot.autoconfigure.jooq.SqlDialectLookup.getDialect(SqlDialectLookup.java:50)
    at org.springframework.boot.autoconfigure.jooq.JooqProperties.determineSqlDialect(JooqProperties.java:58)
    at org.springframework.boot.autoconfigure.jooq.JooqAutoConfiguration$DslContextConfiguration.jooqConfiguration(JooqAutoConfiguration.java:94)
...

This pull request wrap connection declaration in try-with-resource to fix connection leak.

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[mhalbritter]

Put into the 3.2.x bucket, as 3.1.x doesn't contain the bug.

[mhalbritter]

Thank you very much and congratulations on your first contribution 🎉!