Apply suggestions from code review

Author: 0x2b3bfa0

src/cml.js

@@ -404,8 +404,8 @@ class CML {
   async startRunner(opts = {}) {
     const env = {};
     const sensitive =
-      ['CML_RUNNER_SENSITIVE_ENV'] +
-      process.env.CML_RUNNER_SENSITIVE_ENV.split(':');
+      ['_CML_RUNNER_SENSITIVE_ENV'] +
+      process.env._CML_RUNNER_SENSITIVE_ENV.split(':');
     for (const variable in process.env)
       if (!sensitive.includes(variable)) env[variable] = process.env[variable];
     return await this.getDriver().startRunner({ ...opts, env });