params = {
    'action': 'verifyQuotaAndCreateV2',
    'decorationId': 'com.linkedin.voyager.dash.deco.relationships.InvitationCreationResultWithInvitee-2',
}

json_data = {
    'invitee': {
        'inviteeUnion': {
            'memberProfile': 'urn:li:fsd_profile:ACoAAC7dfKwB45XKfm81_mumQHoCYvpgghHrxfQ',
        },
    },
    'customMessage': 'Hey',
}

response = requests.post(
    'https://www.linkedin.com/voyager/api/voyagerRelationshipsDashMemberRelationships',
    params=params,
    cookies=cookies,
    headers=headers,
    json=json_data,
)

print(response)
print(json.dumps(response.json(), indent=4))