Update matrix-sdk to latest Git

There have been major changes since the last release a year ago; including
a switch from sled to sqlite, which will make it easier to inspect the data

Cargo.toml

@@ -46,7 +46,7 @@ nonempty = { version = "0.8.1", features = ["serialize"] }
 signal-hook = "0.3.17"
 
 # Matrix
-matrix-sdk = { version = "0.6.2", features = ["eyre", "markdown"] }
+matrix-sdk = { git = "https://github.com/matrix-org/matrix-rust-sdk.git", rev = "91e7f2f7224b8ada17ab639d60da10dad98aeaf9", features = ["eyre", "markdown"] }
 
 # UI
 crossterm = { version = "0.27.0", features = ["serde", "event-stream"] }