Fix build error with clap v3 beta, bump to latest beta.

Clap short options have changed to character types in clap version 3.  A
bug in clap 3.0.0-beta1 was also causing a compilation failure (tested
with rustc v1.5.0).  Bump clap version to 3.0.0-beta2.

Cargo.toml

@@ -47,7 +47,7 @@ members = [ "tester" ]
 [dependencies]
 # Default features disabled so they can be explicitly opted into
 rdedup-lib = { version = "3.1.0", path = "lib", default-features = false }
-clap = "=3.0.0-beta.1"
+clap = "=3.0.0-beta.2"
 log = "0.4.11"
 hex = "0.4.2"
 rpassword = "4.0"

src/bin.rs

@@ -316,24 +316,24 @@ fn create_logger(verbosity: u32, timing_verbosity: u32) -> slog::Logger {
 #[derive(Debug, Clap)]
 #[clap(author, about = "Data deduplication toolkit")]
 struct CliOpts {
-    #[clap(name = "dir", short = "d", long, value_name = "PATH")]
+    #[clap(name = "dir", short = 'd', long, value_name = "PATH")]
     /// Path to rdedup repository. Override `RDEDUP_DIR` environment variable
     repo_dir: Option<std::ffi::OsString>,
 
     #[clap(
-        short = "u",
+        short = 'u',
         long = "repo",
         conflicts_with = "dir",
         value_name = "URI"
     )]
     /// Rdedup repository URI. Override the `RDEDUP_URI` environment variable
     repo_uri: Option<std::ffi::OsString>,
 
-    #[clap(short = "v", parse(from_occurrences))]
+    #[clap(short = 'v', parse(from_occurrences))]
     /// Increase debugging level for general messages
     verbose: u8,
 
-    #[clap(short = "t", parse(from_occurrences))]
+    #[clap(short = 't', parse(from_occurrences))]
     /// Increase debugging level for timings
     verbose_timings: u8,