Update buildpack name/keywords

To make the name consistent with our other CNBs, eg:
https://github.com/heroku/buildpacks-python/blob/ee25c70c647a2d5d11b19bfc2a4bc1ab5598138c/buildpack.toml#L6
https://github.com/heroku/buildpacks-nodejs/blob/df5f1de2e6fde1ef98701740f80bf83b2975bedd/meta-buildpacks/nodejs/buildpack.toml#L6

And also to add some additional keywords.

See also:
heroku/cnb-builder-images#408

buildpack.toml

@@ -3,10 +3,10 @@ api = "0.10"
 [buildpack]
 id = "heroku/deb-packages"
 version = "0.0.1"
-name = "Heroku .deb Packages Buildpack"
+name = "Heroku .deb Packages"
 description = "Heroku's buildpack for installing .deb system packages."
 homepage = "https://github.com/heroku/buildpacks-deb-packages"
-keywords = ["deb", "debian", "packages"]
+keywords = ["deb", "debian", "packages", "apt", "heroku"]
 
 [[buildpack.licenses]]
 type = "Apache-2.0"