fix: make unit tests runnable in a Maven project

[sekikn]

Description

• This PR fixes the generated Maven project not to ignore the unit tests. I tested it as follows:

$ asyncapi generate fromTemplate tests/mocks/kafka.yml . -o /tmp/kafka -p maven=true
$ cd /tmp/kafka
$ mvn clean install

(snip)

[INFO] --- surefire:3.5.4:test (default-test) @ untitled ---
[INFO] Using configured provider org.apache.maven.surefire.junit4.JUnit4Provider
[INFO] 
[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.asyncapi.SimpleKafkaTest

(snip)

[INFO] 
[INFO] Results:
[INFO] 
[ERROR] Errors: 
[ERROR]   ApplicationTests.contextLoads » IllegalState Failed to load ApplicationContext for [MergedContextConfiguration@1952ad9d testClass = com.asyncapi.ApplicationTests, locations = [], classes = [com.asyncapi.Application], contextInitializerClasses = [], activeProfiles = [], propertySourceLocations = [], propertySourceProperties = ["org.springframework.boot.test.context.SpringBootTestContextBootstrapper=true"], contextCustomizers = [org.springframework.boot.test.context.filter.ExcludeFilterContextCustomizer@9d5509a, org.springframework.boot.test.json.DuplicateJsonObjectContextCustomizerFactory$DuplicateJsonObjectContextCustomizer@7eac9008, org.springframework.boot.test.mock.mockito.MockitoContextCustomizer@0, org.springframework.boot.test.web.client.TestRestTemplateContextCustomizer@5dda768f, org.springframework.boot.test.autoconfigure.actuate.observability.ObservabilityContextCustomizerFactory$DisableObservabilityContextCustomizer@1f, org.springframework.boot.test.autoconfigure.properties.PropertyMappingContextCustomizer@0, org.springframework.boot.test.autoconfigure.web.servlet.WebDriverContextCustomizer@6200f9cb, org.springframework.boot.test.context.SpringBootTestAnnotation@e789c798], contextLoader = org.springframework.boot.test.context.SpringBootContextLoader, parent = null]
[ERROR]   TestcontainerKafkaTest » IllegalState Could not find a valid Docker environment. Please see logs and check configuration
[INFO] 
[ERROR] Tests run: 4, Failures: 0, Errors: 2, Skipped: 0

(2 tests out of 4 failed in the example above, but they are different issues from #459. One should be fixed once #456 is merged, and the other will be addressed in another PR)

• This PR also incorporates fix: remove max generator version #442 to make npm t pass.

Related issue(s)

Resolves #459