Raise the minimum supported version of Gradle to 7.5

[wilkinsona]

This is blocked until 7.5 has been released.

[mhalbritter]

I think we missed to adapt org.springframework.boot.gradle.plugin.SpringBootPlugin#verifyGradleVersion. It still reads:

	private void verifyGradleVersion() {
		GradleVersion currentVersion = GradleVersion.current();
		if (currentVersion.compareTo(GradleVersion.version("7.4")) < 0) {
			throw new GradleException("Spring Boot plugin requires Gradle 7.x (7.4 or later). "
					+ "The current version is " + currentVersion);
		}
	}

[wilkinsona]

Good catch. We should fix that. Can you please open an issue for it?