Ignore recently failing Princess tests (#1629)

Ignores three verification tests `invalid/Generics2`,
`invalid/Overrides`, and `invalid/MyTuple3` that fail on recent Princess
builds.

I'll separately investigate why the tests fail (throwing exceptions in
Princess).

frontends/common/src/it/scala/stainless/verification/VerificationSuite.scala

@@ -157,6 +157,7 @@ class VerificationSuite extends VerificationComponentTestSuite {
       "verification/invalid/FiniteSort",
       "verification/invalid/Float8",
       "verification/invalid/ForallAssoc",
+      "verification/invalid/Generics2",
       "verification/invalid/HiddenOverride",
       "verification/invalid/HOInvocations",
       "verification/invalid/i497",
@@ -171,7 +172,9 @@ class VerificationSuite extends VerificationComponentTestSuite {
       "verification/invalid/LawsExampleInvalid",
       "verification/invalid/ListOperations",
       "verification/invalid/Lists",
+      "verification/invalid/MyTuple3",
       "verification/invalid/Nested15",
+      "verification/invalid/Overrides",
       "verification/invalid/PackedFloat8",
       "verification/invalid/PartialSplit",
       "verification/invalid/PositiveMap",