Example SSE: lock the versions of used Vue package so the example runs. (#514)

Also fix a bootstrap path that didnt work.

Co-authored-by: Miłosz Smółka <milosz.smolka@gmail.com>

Author: thpk

_examples/real-world-examples/server-sent-events/server/public/index.html

@@ -44,10 +44,10 @@
 
 <script src="https://code.jquery.com/jquery-3.4.1.slim.min.js" integrity="sha384-J6qa4849blE2+poT4WnyKhv5vZF5SrPo0iEjwBvKU7imGFAV0wwj1yYfoRSJoZ+n" crossorigin="anonymous"></script>
 <script src="https://cdn.jsdelivr.net/npm/popper.js@1.16.0/dist/umd/popper.min.js" integrity="sha384-Q6E9RHvbIyZFJoft+2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo" crossorigin="anonymous"></script>
-<script src="https://stacjjkpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js" integrity="sha384-wfSDF2E50Y2D1uUdj0O3uMBJnjuUD4Ih7YwaYd1iqfktj0Uod8GCExl3Og8ifwB6" crossorigin="anonymous"></script>
+<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js" integrity="sha384-wfSDF2E50Y2D1uUdj0O3uMBJnjuUD4Ih7YwaYd1iqfktj0Uod8GCExl3Og8ifwB6" crossorigin="anonymous"></script>
 
-<script src="https://unpkg.com/vue/dist/vue.js"></script>
-<script src="https://unpkg.com/vue-router/dist/vue-router.js"></script>
+<script src="https://unpkg.com/vue@2.7.16/dist/vue.js"></script>
+<script src="https://unpkg.com/vue-router@3.6.5/dist/vue-router.js"></script>
 <script src="https://cdn.jsdelivr.net/npm/vue-resource@1.3.5"></script>
 
 <script type="text/x-template" id="feeds-list">