Update Gradle to 7.6 from 7.3

[vlsi]

No description provided.

[vlsi]

For some reason, the tests fail with

FAILURE   0.0sec, org.apache.jmeter.testelement.AbstractTestElementSpec > set all properties as temporary when using a MultiProperty
    java.lang.NoClassDefFoundError: Could not initialize class org.spockframework.mock.runtime.CglibMockFactory$ConstructorFriendlyEnhancer
        at org.spockframework.mock.runtime.CglibMockFactory.createMock(CglibMockFactory.java:24)
        at org.spockframework.mock.runtime.ProxyBasedMockFactory.create(ProxyBasedMockFactory.java:45)
        at org.spockframework.mock.runtime.JavaMockFactory.createInternal(JavaMockFactory.java:58)
        at org.spockframework.mock.runtime.JavaMockFactory.create(JavaMockFactory.java:38)
        at org.spockframework.mock.runtime.CompositeMockFactory.create(CompositeMockFactory.java:44)
        at org.spockframework.lang.SpecInternals.createMock(SpecInternals.java:50)
        at org.spockframework.lang.SpecInternals.createMockImpl(SpecInternals.java:305)
        at org.spockframework.lang.SpecInternals.createMockImpl(SpecInternals.java:295)
        at org.spockframework.lang.SpecInternals.SpyImpl(SpecInternals.java:168)
        at org.apache.jmeter.testelement.AbstractTestElementSpec.set all properties as temporary when using a MultiProperty(AbstractTestElementSpec.groovy:49)

[vlsi]

I guess it is related to gradle/gradle#20999 where previously Gradle added add-opens on its own, and now it does not really do so.