fix clap version

[hanqitech]

When I try to compile project 2, I met error messages .
Command
cargo run -- --upstream 171.67.215.200:80
message
error[E0432]: unresolved import clap::Clap--> src/main.rs:4:5 | 4 | use clap::Clap; | ^^^^^^^^^^ noClap` in the root

error: cannot determine resolution for the derive macro Clap
--> src/main.rs:10:10
|
10 | #[derive(Clap, Debug)]
| ^^^^
|
= note: import resolution is stuck, try simplifying macro imports

error: cannot find attribute clap in this scope
--> src/main.rs:11:3
|
11 | #[clap(about = "Fun with load balancing")]
| ^^^^
|
= note: clap is in scope, but it is a crate, not an attribute

error: cannot find attribute clap in this scope
--> src/main.rs:13:7
|
13 | #[clap(
| ^^^^
|
= note: clap is in scope, but it is a crate, not an attribute

error: cannot find attribute clap in this scope
--> src/main.rs:20:7
|
20 | #[clap(short, long, about = "Upstream host to forward requests to")]
| ^^^^
|
= note: clap is in scope, but it is a crate, not an attribute

error: cannot find attribute clap in this scope
--> src/main.rs:22:7
|
22 | #[clap(
| ^^^^
|
= note: clap is in scope, but it is a crate, not an attribute

error: cannot find attribute clap in this scope
--> src/main.rs:28:7
|
28 | #[clap(
| ^^^^
|
= note: clap is in scope, but it is a crate, not an attribute

error: cannot find attribute clap in this scope
--> src/main.rs:34:7
|
34 | #[clap(
| ^^^^
|
= note: clap is in scope, but it is a crate, not an attribute

error[E0599]: no function or associated item named parse found for struct CmdOptions in the current scope
--> src/main.rs:70:31
|
12 | struct CmdOptions {
| ----------------- function or associated item parse not found for this struct
...
70 | let options = CmdOptions::parse();
| ^^^^^ function or associated item not found in CmdOptions
|
= help: items from traits can only be used if the trait is implemented and in scope
= note: the following traits define an item parse, perhaps you need to implement one of them:
candidate #1: Parser
candidate #2: TypedValueParser

Some errors have detailed explanations: E0432, E0599.
For more information about an error, try rustc --explain E0432.
error: could not compile balancebeam (bin "balancebeam") due to 9 previous errors`

I doubt it's about Crate clap's version ,So I updated it's version and did a little change ,then It compiles .