res.cookie option with sameSite 'none' throws TypeError: option sameSite is invalid at Object.serialize

### Related issues

I found the issue for Express framework
https://github.com/expressjs/express/issues/3958
and looks it was fixed there.

### [REQUIRED] Version info

node: v10.16.3

**firebase-tools:**

8.0.0.

### [REQUIRED] Test case

export const sameSiteCookie = functions.https.onRequest((req, res) => {
cors(req, res, () => {
const expiresIn = 60 * 60 * 24 * 5 * 1000;
const options: any = {
maxAge: expiresIn,
httpOnly: true,
secure: true,
sameSite: 'none',
};
res.cookie('testCKI', 'value123', options);
res.end(JSON.stringify({
data: {
status: 'success'
}
}));
});
});

### [REQUIRED] Steps to reproduce

calling the cloud function above

### [REQUIRED] Expected behavior

set cookie value to SameSite=Never

### [REQUIRED] Actual behavior

TypeError: option sameSite is invalid at Object.serialize (/worker/node_modules/cookie/index.js:174:15) at ServerResponse.res.cookie (/worker/node_modules/express/lib/response.js:853:36) at cors (/srv/lib/index.js:106:13) at cors (/srv/node_modules/cors/lib/index.js:188:7) at /srv/node_modules/cors/lib/index.js:224:17 at originCallback (/srv/node_modules/cors/lib/index.js:214:15) at /srv/node_modules/cors/lib/index.js:219:13 at optionsCallback (/srv/node_modules/cors/lib/index.js:199:9) at corsMiddleware (/srv/node_modules/cors/lib/index.js:204:7) at exports.sessionLogin.functions.https.onRequest (/srv/lib/index.js:98:5)

### Were you able to successfully deploy your functions?

no error messages seen

Start with the supplied TypeScript test case and the stack trace at node_modules/cookie/index.js:174 and express/lib/response.js:853; compare the dependency behavior with related Express issue #3958. Reproduce with firebase-tools 8.0.0 and confirm that res.cookie accepts sameSite: 'none' and emits the expected cookie without the TypeError.

索引モデルが issue の本文から書いたものです。