Add FoundationDB to CI (#33)

Travis CI builds CouchDB for testing `couchdb-config`.
`couchdb`'s `main` branch now requires FoundationDB to be present for builds.

This commit adds FoundationDB to Travis CI.

.travis.yml

@@ -9,10 +9,14 @@ sudo: false
 
 addons:
   apt:
+    update: true
     packages:
       - libmozjs185-dev
 
 before_install:
+  - sudo apt-get install -y curl python
+  - curl -sO https://www.foundationdb.org/downloads/6.2.28/ubuntu/installers/foundationdb-clients_6.2.28-1_amd64.deb
+  - sudo dpkg -i foundationdb-clients_6.2.28-1_amd64.deb
   - git clone --depth 1 https://github.com/apache/couchdb
 
 before_script: