fix: Disable postcard use temporarily

[Veykril]

I am getting constant failed to write request: The length of a sequence must be known (rust-analyzer macro-error) errors it seems.

We'll need to beta backport this

[ChayimFriedman2]

If this needs a beta backport we need to hurry, as it'll become stable soon.

[Veykril]

ah no, for the next beta (iirc we branched yesterday / branch today?), so we have an entire cycle time

[tisonkun]

I bumped to nightly-2025-12-08 but it seems the issue remains at least on VS Code with RA.

[ChayimFriedman2]

@tisonkun I believe this was not yet synced into rust-lang/rust back then.

[tisonkun]

@tisonkun I believe this was not yet synced into rust-lang/rust back then.

Is there any channel for subscription or where I can get the sync status?

[ShoyuVanilla]

You can search for subtree syncs like rust-lang/rust#149766 but getting notification for that is difficult as you have to check whether they are merged and they are included to the latest nightly rust toolchain release.
IMHO, rust-analyzer as a rustup component is not a recommended release channel