fix cpp20

Examples/Algorithms/GeneratorsPythia8/ActsExamples/Generators/Pythia8ProcessGenerator.cpp

@@ -118,7 +118,7 @@ Pythia8Generator::operator()(RandomEngine& rng) {
       // TODO can we do this w/o the manual search and position check?
       auto it = std::find_if(
           vertices.begin(), vertices.end(),
-          [=](const SimVertex& other) { return pos4 == other.position4; });
+          [&pos4](const SimVertex& other) { return pos4 == other.position4; });
       if (it != vertices.end()) {
         particleId.setVertexSecondary(std::distance(vertices.begin(), it));
         it->outgoing.insert(particleId);