See which boost versions are available

.travis.yml

@@ -8,6 +8,7 @@ before_install:
   - sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
   - sudo add-apt-repository -y ppa:mhier/libboost-latest
   - sudo apt update
+  - sudo apt-cache search libboost
   - sudo apt -y install libboost-dev libboost-context-dev g++-9
 script:
   - npm run test