Bumped version to 7.0.0

[hiranya911]

Also updated one of the test configuration files to prevent the following error:

+ [email protected]
added 278 packages in 12.228s
> tsc -p tsconfig.json
node_modules/google-auth-library/build/src/auth/oauth2client.d.ts:280:37 - error TS2583: Cannot find name 'Map'. Do you need to change your target library? Try changing the `lib` compiler option to es2015 or later.

280     protected refreshTokenPromises: Map<string, Promise<GetTokenResponse>>;
                                        ~~~


Found 1 error.