Set SemverCompatible to false for Conan packages (#21275) (#21366)

Backport of #21275

integrations/api_packages_conan_test.go

@@ -266,7 +266,7 @@ func TestPackageConan(t *testing.T) {
 
 				pd, err := packages.GetPackageDescriptor(db.DefaultContext, pvs[0])
 				assert.NoError(t, err)
-				assert.NotNil(t, pd.SemVer)
+				assert.Nil(t, pd.SemVer)
 				assert.Equal(t, name, pd.Package.Name)
 				assert.Equal(t, version1, pd.Version.Version)
 				assert.IsType(t, &conan_module.Metadata{}, pd.Metadata)