Bump testcontainers.version from 1.20.3 to 1.20.4

Bumps `testcontainers.version` from 1.20.3 to 1.20.4.

Updates `org.testcontainers:testcontainers` from 1.20.3 to 1.20.4
- [Release notes](https://github.com/testcontainers/testcontainers-java/releases)
- [Changelog](https://github.com/testcontainers/testcontainers-java/blob/main/CHANGELOG.md)
- [Commits](testcontainers/testcontainers-java@1.20.3...1.20.4)

Updates `org.testcontainers:junit-jupiter` from 1.20.3 to 1.20.4
- [Release notes](https://github.com/testcontainers/testcontainers-java/releases)
- [Changelog](https://github.com/testcontainers/testcontainers-java/blob/main/CHANGELOG.md)
- [Commits](testcontainers/testcontainers-java@1.20.3...1.20.4)

---
updated-dependencies:
- dependency-name: org.testcontainers:testcontainers
  dependency-type: direct:development
  update-type: version-update:semver-patch
- dependency-name: org.testcontainers:junit-jupiter
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

pom.xml

@@ -28,7 +28,7 @@
     <docker-image-tag>${project.version}</docker-image-tag>
 
     <autograding-model.version>4.2.0</autograding-model.version>
-    <testcontainers.version>1.20.3</testcontainers.version>
+    <testcontainers.version>1.20.4</testcontainers.version>
     <github-api.version>1.326</github-api.version>
 
     <jib-maven-plugin.version>3.4.4</jib-maven-plugin.version>