Add CouchDB matrix to and remove erlang 19 from CI (#34)

diff --git a/.travis.yml b/.travis.yml
index 141d476..89977c6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,7 +3,10 @@
 otp_release:
   - 21.1
   - 20.3
-  - 19.3
+
+env:
+  - COUCHDB_BRANCH=main
+  - COUCHDB_BRANCH=3.x
 
 sudo: false
 
@@ -17,10 +20,12 @@
   - 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
+  - git clone --no-single-branch --depth 1 https://github.com/apache/couchdb
+
 
 before_script:
   - cd couchdb
+  - git checkout origin/${COUCHDB_BRANCH}
   - ./configure --disable-docs --disable-fauxton
   - cp -r ../!(couchdb) ./src/config
   - make