cli: migrate from gumdrop to clap v3 (#379)

`gumdrop` was originally chosen for its minimalist set of dependencies,
but `clap` v3 has a slimmed down set of dependencies and better UX.

Cargo.lock

@@ -105,6 +105,45 @@ dependencies = [
  "inout",
 ]
 
+[[package]]
+name = "clap"
+version = "3.1.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d2dbdf4bdacb33466e854ce889eee8dfd5729abf7ccd7664d0a2d60cd384440b"
+dependencies = [
+ "atty",
+ "bitflags",
+ "clap_derive",
+ "clap_lex",
+ "indexmap",
+ "lazy_static",
+ "strsim",
+ "termcolor",
+ "textwrap",
+]
+
+[[package]]
+name = "clap_derive"
+version = "3.1.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "25320346e922cffe59c0bbc5410c8d8784509efb321488971081313cb1e1a33c"
+dependencies = [
+ "heck",
+ "proc-macro-error",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "clap_lex"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a37c35f1112dad5e6e0b1adaff798507497a18fceeb30cceb3bae7d1427b9213"
+dependencies = [
+ "os_str_bytes",
+]
+
 [[package]]
 name = "const-oid"
 version = "0.7.1"
@@ -332,24 +371,16 @@ dependencies = [
 ]
 
 [[package]]
-name = "gumdrop"
-version = "0.8.1"
+name = "hashbrown"
+version = "0.11.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5bc700f989d2f6f0248546222d9b4258f5b02a171a431f8285a81c08142629e3"
-dependencies = [
- "gumdrop_derive",
-]
+checksum = "ab5ef0d4909ef3724cc8cce6ccc8572c5c817592e9285f5464f8e86f8bd3726e"
 
 [[package]]
-name = "gumdrop_derive"
-version = "0.8.1"
+name = "heck"
+version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "729f9bd3449d77e7831a18abfb7ba2f99ee813dfd15b8c2167c9a54ba20aa99d"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
-]
+checksum = "2540771e65fc8cb83cd6e8a237f70c319bd5c29f78ed1084ba5d50eeac86f7f9"
 
 [[package]]
 name = "hermit-abi"
@@ -375,6 +406,16 @@ version = "2.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9a3a5bfb195931eeb336b2a7b4d761daec841b97f947d34394601737a7bba5e4"
 
+[[package]]
+name = "indexmap"
+version = "1.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0f647032dfaa1f8b6dc29bd3edb7bbef4861b8b8007ebb118d6db284fd59f6ee"
+dependencies = [
+ "autocfg",
+ "hashbrown",
+]
+
 [[package]]
 name = "inout"
 version = "0.1.3"
@@ -511,6 +552,12 @@ version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "624a8340c38c1b80fd549087862da4ba43e08858af025b236e509b6649fc13d5"
 
+[[package]]
+name = "os_str_bytes"
+version = "6.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "029d8d0b2f198229de29dca79676f2738ff952edf3fde542eb8bf94d8c21b435"
+
 [[package]]
 name = "p256"
 version = "0.11.0"
@@ -613,6 +660,30 @@ version = "0.2.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "eb9f9e6e233e5c4a35559a617bf40a4ec447db2e84c20b55a6f83167b7e57872"
 
+[[package]]
+name = "proc-macro-error"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "da25490ff9892aab3fcf7c36f08cfb902dd3e71ca0f9f9517bea02a73a5ce38c"
+dependencies = [
+ "proc-macro-error-attr",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "version_check",
+]
+
+[[package]]
+name = "proc-macro-error-attr"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a1be40180e52ecc98ad80b184934baf3d0d29f979574e439af5a55274b35f869"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "version_check",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.39"
@@ -824,6 +895,12 @@ dependencies = [
  "der 0.6.0",
 ]
 
+[[package]]
+name = "strsim"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
+
 [[package]]
 name = "subtle"
 version = "2.4.1"
@@ -859,6 +936,12 @@ dependencies = [
  "winapi-util",
 ]
 
+[[package]]
+name = "textwrap"
+version = "0.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b1141d4d61095b28419e22cb0bbf02755f5e54e0526f97f1e3d1d160e60885fb"
+
 [[package]]
 name = "thiserror"
 version = "1.0.31"
@@ -1018,8 +1101,8 @@ dependencies = [
 name = "yubikey-cli"
 version = "0.6.0-pre"
 dependencies = [
+ "clap",
  "env_logger",
- "gumdrop",
  "lazy_static",
  "log",
  "sha2 0.9.9",