Update chrome version to 78 (#11765)

uitest/src/test/java/com/vaadin/tests/VerifyBrowserVersionTest.java

             // Chrome version does not necessarily match the desired version
             // because of auto updates...
             browserIdentifier = getExpectedUserAgentString(
-                    getDesiredCapabilities()) + "77";
+                    getDesiredCapabilities()) + "78";
         } else if (BrowserUtil.isFirefox(getDesiredCapabilities())) {
             browserIdentifier = getExpectedUserAgentString(
                     getDesiredCapabilities()) + "58";