fix(ci): do not test on unsupported versions

BREAKING CHANGE: exist versions 2.2 and 3.6.1 are no longer officially supported.

Author: line-o

.travis.yml

@@ -32,7 +32,6 @@ env:
   - img=existdb/existdb:latest
   - img=existdb/existdb:release
   - img=existdb/existdb:4.7.1
-  - img=evolvedbinary/exist-db:eXist-3.6.1-minimal
 
 notifications:
   email: false

appveyor.yml

@@ -1,13 +1,11 @@
 version: 1.2.{build}
 
 environment:
-  NODE_VERSION: 8
+  NODE_VERSION: 12
 
   matrix:
   - EXIST_VERSION: 5.0.0-RC4
   - EXIST_VERSION: 4.7.1
-  - EXIST_VERSION: 3.6.1
-  - EXIST_VERSION: 2.2
 
 install:
   - ps: Install-Product node $env:NODE_VERSION