chore(deps): require proton SDK 0.7.1

0.7.1 sends TCP keepalives on its connections, so a link that dies
silently is noticed instead of leaving a request waiting on a dead
socket until its timeout.

Cargo.toml

@@ -15,8 +15,8 @@ keywords = ["proton", "drive", "fuse", "sync", "linux"]
 categories = ["filesystem", "command-line-utilities"]
 
 [workspace.dependencies]
-proton-sdk = { version = "0.7.0" }
-proton-drive-rs = { version = "0.7.0" }
+proton-sdk = { version = "0.7.1" }
+proton-drive-rs = { version = "0.7.1" }
 
 # Internal crates.
 pdfs-core = { path = "crates/pdfs-core" }