anchor keys sync change Anchor.toml [provider] unexpected

[xG0Ian]

when use custom rpc:

[provider]
cluster = "https://rpc.ankr.com/solana_devnet"
wallet = "~/.config/solana/id.json"

and run:

1. rm target/deploy/*-keypair.json
2. anchor keys sync

Anchor.toml will be changed to:

[provider]
cluster = ["https://rpc.ankr.com/solana_devnet", "wss://rpc.ankr.com/solana_devnet"]
wallet = "~/.config/solana/id.json"

and we will get this error from anchor keys sync:

Workspace configuration error: Unable to deserialize config: TOML parse error at line 14, column 11
   |
14 | cluster = ["https://rpc.ankr.com/solana_devnet", "wss://rpc.ankr.com/solana_devnet"]
   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
invalid type: sequence, expected string or map

[acheroncrypto]

Thanks for creating the issue. However, a similar issue exists in #3222, so I'm closing this one as duplicate to not divert attention.