travis: remove rust checks

rust ci was not part of stable 1.9.

Signed-off-by: Jose Carlos Venegas Munoz <jose.carlos.venegas.munoz@intel.com>

.travis.yml

@@ -1,33 +0,0 @@
-# Copyright (c) 2019 Ant Financial
-#
-# SPDX-License-Identifier: Apache-2.0
-#
-
-sudo: required
-dist: bionic
-
-os:
-    - linux
-
-language: rust
-rust:
-    - stable
-
-env:
-    - target_branch=$TRAVIS_BRANCH RUST_AGENT=yes
-
-before_install:
-    - "ci/setup.sh"
-    - "ci/install_go.sh"
-    - "ci/install_rust.sh"
-    - "ci/static-checks.sh"
-
-# need to install rust from scratch?
-# still need go to download github.com/kata-containers/tests
-# which is already installed?
-
-install:
-    - cd ${TRAVIS_BUILD_DIR}/src/agent && make
-
-script:
-    - cd ${TRAVIS_BUILD_DIR}/src/agent && make check