Update dependency org.testcontainers:postgresql to v1.20.4 (#723)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

gradle/libs.versions.toml

@@ -16,7 +16,7 @@ mockk = "1.13.14"
 springMockk = "4.0.2"
 greenmail = "2.1.2"
 flyway = "10.15.0"
-testcontainers = "1.19.8"
+testcontainers = "1.20.4"
 jooq = "3.19.16"
 jooqPlugin = "9.0"
 postgresql = "42.7.4"