chore: Pin clap to 3.0.0-beta.2 (#260)

Avoids errors like this:

error[E0658]: arbitrary expressions in key-value attributes are unstable
 --> /Users/ericswanson/.cargo/registry/src/github.com-1ecc6299db9ec823/clap-3.0.0-beta.4/src/lib.rs:8:10
  |
8 | #![doc = include_str!("../README.md")]
  |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #78835 <rust-lang/rust#78835> for more information

   Compiling binread v2.1.1
   Compiling logos v0.12.0
error[E0658]: use of unstable library feature 'osstring_ascii'
   --> /Users/ericswanson/.cargo/registry/src/github.com-1ecc6299db9ec823/clap-3.0.0-beta.4/src/parse/matches/matched_arg.rs:130:19
    |
130 |                 v.eq_ignore_ascii_case(val)
    |                   ^^^^^^^^^^^^^^^^^^^^
    |
    = note: see issue #70516 <rust-lang/rust#70516> for more information

icx-asset/Cargo.toml

@@ -18,7 +18,8 @@ include = ["src", "Cargo.toml", "../LICENSE", "README.md"]
 anyhow = "1.0.34"
 candid = "0.7.4"
 chrono = "0.4.19"
-clap = "3.0.0-beta.2"
+clap = "=3.0.0-beta.2"
+clap_derive = "=3.0.0-beta.2"
 delay = "0.3.1"
 garcon = "0.2.2"
 humantime = "2.0.1"

icx-cert/Cargo.toml

@@ -17,7 +17,8 @@ include = ["src", "Cargo.toml", "../LICENSE", "README.md"]
 [dependencies]
 anyhow = "1.0"
 base64 = "0.13"
-clap = "3.0.0-beta.2"
+clap = "=3.0.0-beta.2"
+clap_derive = "=3.0.0-beta.2"
 chrono = "0.4.19"
 hex = "0.4.2"
 ic-agent = { path = "../ic-agent", version = "0.8" }

icx-proxy/Cargo.toml

@@ -18,7 +18,8 @@ path = "src/main.rs"
 
 [dependencies]
 anyhow = "1.0.34"
-clap = "3.0.0-beta.2"
+clap = "=3.0.0-beta.2"
+clap_derive = "=3.0.0-beta.2"
 garcon = { version = "0.2.3", features = ["async"] }
 hex = "0.4.3"
 hyper = { version = "0.14.11", features = ["full"] }

icx/Cargo.toml

@@ -19,7 +19,8 @@ path = "src/main.rs"
 [dependencies]
 anyhow = { version = "1.0", features = ["backtrace"] }
 candid = "0.7.4"
-clap = "3.0.0-beta.1"
+clap = "=3.0.0-beta.2"
+clap_derive = "=3.0.0-beta.2"
 garcon = { version = "0.2.3", features = ["async"] }
 hex = "0.4.2"
 humantime = "2.0.1"

zzz-release/Cargo.toml

@@ -8,6 +8,7 @@ edition = "2018"
 [dependencies]
 anyhow = "1.0.40"
 cargo_metadata = "0.14.0"
-clap = "3.0.0-beta.2"
+clap = "=3.0.0-beta.2"
+clap_derive = "=3.0.0-beta.2"
 git2 = "0.13.20"
 toml-parse = "0.2.11"