Add admin_conversations_bulkSetProperties to WebClient #1992

admin.conversations.bulkSetProperties is a public Web API method, but WebClient has no wrapper for it, so you have to call it through client.api_call(...). I've opened #1991 to add admin_conversations_bulkSetProperties to the sync, async and legacy clients.

Category (place an x in each of the [ ])

• slack_sdk.web.WebClient (sync/async) (Web API client)
• slack_sdk.webhook.WebhookClient (sync/async) (Incoming Webhook, response_url sender)
• slack_sdk.models (UI component builders)
• slack_sdk.oauth (OAuth Flow Utilities)
• slack_sdk.socket_mode (Socket Mode client)
• slack_sdk.audit_logs (Audit Logs API client)
• slack_sdk.scim (SCIM API client)
• slack_sdk.rtm (RTM client)
• slack_sdk.signature (Request Signature Verifier)

Requirements

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