build(deps): update bitflags requirement from 1.2.1 to 2.6.0

Updates the requirements on [bitflags](https://github.com/bitflags/bitflags) to permit the latest version.
- [Release notes](https://github.com/bitflags/bitflags/releases)
- [Changelog](https://github.com/bitflags/bitflags/blob/main/CHANGELOG.md)
- [Commits](bitflags/bitflags@1.2.1...2.6.0)

---
updated-dependencies:
- dependency-name: bitflags
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

varlink-cli/Cargo.toml

@@ -25,4 +25,4 @@ clap = "2.33.0"
 colored_json = "2.1.0"
 anyhow = "1.0.93"
 libc = { version = "0.2.126", default-features = false }
-bitflags = "1.2.1"
+bitflags = "2.6.0"