fix "travic ci" config

* @types/node should be compatible with the @electron built-in @types/node version (@electron v12 comes with node v14 and respective typings)

Author: vladimiry

.travis.yml

@@ -18,7 +18,7 @@ before_install:
 install:
   - yarn install --pure-lockfile --network-timeout 1000000
   - yarn add rxjs@6
-  - yarn add electron@6
+  - yarn add electron@12
 script:
   - npx envinfo
   - node --version