Update README.md with GAE Java 8 deprecation

[diegomarquezp]

Installation instructions are not added since there is a message indicating that they are found in cloud.google.com

[diegomarquezp]

Tests failing with:

2024-01-09T21:08:25.5052977Z Tests run: 7, Failures: 2, Errors: 0, Skipped: 0, Time elapsed: 0.06 s <<< FAILURE! - in com.google.cloud.tools.eclipse.appengine.libraries.model.CloudLibrariesInPluginXmlTest

2024-01-09T21:08:25.5056093Z testObjectifyLibraryConfig(com.google.cloud.tools.eclipse.appengine.libraries.model.CloudLibrariesInPluginXmlTest)  Time elapsed: 0.002 s  <<< FAILURE!
2024-01-09T21:08:25.5057940Z java.lang.AssertionError: expected:<6.0.9> but was:<6.1.1>
2024-01-09T21:08:25.5059007Z 	at org.junit.Assert.fail(Assert.java:88)
2024-01-09T21:08:25.5059968Z 	at org.junit.Assert.failNotEquals(Assert.java:834)
2024-01-09T21:08:25.5060961Z 	at org.junit.Assert.assertEquals(Assert.java:118)
2024-01-09T21:08:25.5061981Z 	at org.junit.Assert.assertEquals(Assert.java:144)
2024-01-09T21:08:25.5064442Z 	at com.google.cloud.tools.eclipse.appengine.libraries.model.CloudLibrariesInPluginXmlTest.testObjectifyLibraryConfig(CloudLibrariesInPluginXmlTest.java:171)
2024-01-09T21:08:25.5066821Z 	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2024-01-09T21:08:25.5068537Z 	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
2024-01-09T21:08:25.5070565Z 	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
2024-01-09T21:08:25.5072277Z 	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
...

2024-01-09T21:08:25.5136244Z testObjectify6LibraryConfig(com.google.cloud.tools.eclipse.appengine.libraries.model.CloudLibrariesInPluginXmlTest)  Time elapsed: 0.056 s  <<< FAILURE!
2024-01-09T21:08:25.5137844Z java.lang.AssertionError: 
2024-01-09T21:08:25.5138176Z 
2024-01-09T21:08:25.5138572Z Expected: is "31.1-jre"
2024-01-09T21:08:25.5139061Z      but: was "32.1.2-jre"
2024-01-09T21:08:25.5139742Z 	at org.hamcrest.MatcherAssert.assertThat(MatcherAssert.java:20)
2024-01-09T21:08:25.5140597Z 	at org.junit.Assert.assertThat(Assert.java:956)
2024-01-09T21:08:25.5141319Z 	at org.junit.Assert.assertThat(Assert.java:923)
2024-01-09T21:08:25.5143202Z 	at com.google.cloud.tools.eclipse.appengine.libraries.model.CloudLibrariesInPluginXmlTest.testObjectify6LibraryConfig(CloudLibrariesInPluginXmlTest.java:245)
2024-01-09T21:08:25.5145370Z 	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2024-01-09T21:08:25.5146875Z 	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
2024-01-09T21:08:25.5148596Z 	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
2024-01-09T21:08:25.5149959Z 	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
2024-01-09T21:08:25.5151101Z 	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
2024-01-09T21:08:25.5152498Z 	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
2024-01-09T21:08:25.5153908Z 	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
2024-01-09T21:08:25.5155315Z 	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
2024-01-09T21:08:25.5156541Z 	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
2024-01-09T21:08:25.5157733Z 	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
2024-01-09T21:08:25.5159098Z 	at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
2024-01-09T21:08:25.5160261Z 	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)