Don't update apt

.circleci/config.yml

@@ -20,7 +20,6 @@ jobs:
     - run:
         name: Install rust
         command: |
-          sudo apt-get update
           RUSTUP_HOME=/usr/local/rustup
           CARGO_HOME=/usr/local/cargo
           RUST_VERSION=1.35.0
@@ -42,7 +41,7 @@ jobs:
         name: Setup
         command: |
           set -eux
-          sudo apt-get upgrade -y
+          sudo apt-get update
           sudo apt-get install -y cmake g++ pkg-config jq libcurl4-openssl-dev libelf-dev libdw-dev binutils-dev libiberty-dev
           cargo install cargo-kcov
           mkdir -p /tmp/kcov