CI: Set the variable correctly

.circleci/config.yml

@@ -41,7 +41,7 @@ commands:
           command: |
               echo "export RUST_BACKTRACE=1" >> $BASH_ENV
               echo "export RUST_LOG=glean_core=debug" >> $BASH_ENV
-              echo "export CARGO_NET_GIT_FETCH_WITH_CLI=1" >> $BASH_ENV
+              echo "export CARGO_NET_GIT_FETCH_WITH_CLI=true" >> $BASH_ENV
       - run:
           name: Setup Rust toolchain
           command: |