ci: use node 12.18.0

Jenkinsfile

@@ -33,7 +33,7 @@ def testOnAndroidDevices = false // testOnDevices // FIXME: Our android device i
 def testOnIOSDevices = testOnDevices
 
 // Variables we can change
-def nodeVersion = '10.17.0' // NOTE that changing this requires we set up the desired version on jenkins master first!
+def nodeVersion = '12.18.0' // NOTE that changing this requires we set up the desired version on jenkins master first!
 def npmVersion = 'latest' // We can change this without any changes to Jenkins. 5.7.1 is minimum to use 'npm ci'
 
 // Variables which we assign and share between nodes