The only way to do this is to deny access to sudo for those other users. If you have multiple people with sudo aka admin privileges you can't restrict access to sudo/root and are better off NOT keeping this file on the server. Especially if you don't trust everyone with administrative privileges on the system from not snooping your data.

Permissions to run anything as sudo is essentially equal to having root access but without the root account being unlocked. root has access to everything. You won't be able to stop that access.

Short of removing sudo from those users or adding special sudoers lines to define exactly what commands can be run via sudo by those other sudo-capable users (and nothing else, in this sense 'restricted' admin rights since they can't do just anything with their sudo), you have no options to protect against sudo / root viewing the file.

Other alternatives would be encrypting the file locally on your system BEFORE uploading, such as with gpg encryption or such. In those cases, even if they can access the file, they can't edit or view the contents because they're encrypted, and won't have your decryption codes necessary to read the files, even as root. However that's more complex and a bit outside the scope of the question you asked.