update poms to use tycho 0.24.0 to fix the CI build

Signed-off-by: Florian Thienel <florian@thienel.org>
diff --git a/org.eclipse.vex.repository/category.xml b/org.eclipse.vex.repository/category.xml
index c283766..7608698 100644
--- a/org.eclipse.vex.repository/category.xml
+++ b/org.eclipse.vex.repository/category.xml
@@ -3,10 +3,10 @@
    <description>

       Visual Editor for XML

    </description>

-   <feature url="features/org.eclipse.vex.feature_1.2.0.qualifier.jar" id="org.eclipse.vex.feature" version="1.2.0.qualifier">

+   <feature id="org.eclipse.vex.feature" version="0.0.0">

       <category name="vex_core"/>

    </feature>

-   <feature url="features/org.eclipse.vex.sdk.feature_1.2.0.qualifier.jar" id="org.eclipse.vex.sdk.feature" version="1.2.0.qualifier">

+   <feature id="org.eclipse.vex.feature.source" version="0.0.0">

       <category name="vex_core"/>

    </feature>

    <category-def name="vex_core" label="Visual Editor for XML">