remove Travis config

.travis.yml

-language: go
-
-go:
-  - "1.14.x"
-
-# first part of the GOARCH workaround
-# setting the GOARCH directly doesn't work, since the value will be overwritten later
-# so set it to a temporary environment variable first
-env:
-  - TRAVIS_GOARCH=amd64
-  - TRAVIS_GOARCH=386
-
-# second part of the GOARCH workaround
-# now actually set the GOARCH env variable to the value of the temporary variable set earlier
-before_install:
-  - |
-    go get golang.org/x/tools/cmd/cover;
-    go get github.com/onsi/ginkgo/ginkgo;
-    go get github.com/onsi/gomega;
-  - export GOARCH=$TRAVIS_GOARCH
-  - go env
-
-script:
-  # some tests are randomized. Run them a few times.
-  - for i in `seq 1 10`; do
-      ginkgo -r -v --cover --randomizeAllSpecs --randomizeSuites --trace --progress;
-    done
-
-after_success:
-  - cat go-libp2p-tls.coverprofile > coverage.txt
-  - cat */*.coverprofile >> coverage.txt
-  - bash <(curl -s https://codecov.io/bash) -f coverage.txt
-
-cache:
-  directories: