Test against MongoDB 4.2 stable

.travis.yml

@@ -16,7 +16,7 @@ env:
   global:
     - DRIVER_VERSION=1.6.0alpha3
     - SERVER_DISTRO=ubuntu1604
-    - SERVER_VERSION=4.0.10
+    - SERVER_VERSION=4.2.0
     - DEPLOYMENT=STANDALONE
     - COMPOSER_OPTIONS=
 
@@ -44,7 +44,7 @@ jobs:
       env:
         - COMPOSER_OPTIONS=--prefer-lowest
 
-      # Test older standalone server versions (3.0-3.6)
+      # Test older standalone server versions (3.0-4.0)
     - stage: Test
       php: "7.0"
       dist: trusty
@@ -66,6 +66,10 @@ jobs:
       php: "7.0"
       env:
         - SERVER_VERSION=3.6.13
+    - stage: Test
+      php: "7.3"
+      env:
+        - SERVER_VERSION=4.0.12
 
     # Test other server configurations
     - stage: Test
@@ -94,13 +98,6 @@ jobs:
       env:
         - DEPLOYMENT=SHARDED_CLUSTER_RS
 
-    # Test upcoming server versions
-    - stage: Test
-      php: "7.3"
-      env:
-        - SERVER_VERSION=4.2.0-rc1
-        - DEPLOYMENT=REPLICASET
-
 before_install:
   - pip install "mongo-orchestration>=0.6.7,<1.0" --user `whoami`
   - export SERVER_FILENAME=mongodb-linux-x86_64-${SERVER_DISTRO}-${SERVER_VERSION}