simplifying tests

no need to run on so many browsers now that using standardized-audio-context gives more cross-browser compatability.

.travis.yml

@@ -2,7 +2,7 @@ sudo: false
 dist: bionic
 language: node_js
 node_js:
-- '14'
+    - "14"
 install:
     - npm install
     - git config --global user.email "travis@travis-ci.org"
@@ -21,21 +21,6 @@ jobs:
           os: linux
           addons:
               chrome: stable
-    - stage: test
-      env : BROWSER=chrome
-      os: linux
-      addons:
-        chrome: beta
-    - stage: test
-      env : BROWSER=firefox
-      os: linux
-      addons:
-        firefox: latest
-    - stage: test
-      env : BROWSER=firefox
-      os: linux
-      addons:
-        firefox: latest-beta
         - stage: test
           script:
               - npm run build