Fix cargo audit issues and add non-blocking CI action for cargo audit

[ysaito1001]

cargo audit has reported the following vulnerabilities in smithy-rs:
(from aws/rust-runtime)

Crate:     remove_dir_all
Version:   0.5.3
Title:     Race Condition Enabling Link Following and Time-of-check Time-of-use (TOCTOU)
Date:      2023-02-24
ID:        RUSTSEC-2023-0018
URL:       https://rustsec.org/advisories/RUSTSEC-2023-0018
Solution:  Upgrade to >=0.8.0
Dependency tree:
remove_dir_all 0.5.3
└── tempfile 3.3.0
    ├── rusty-fork 0.3.0
    │   └── proptest 1.0.0
    │       ├── aws-sigv4 0.0.0-smithy-rs-head
    │       │   └── aws-sig-auth 0.0.0-smithy-rs-head
    │       │       └── aws-inlineable 0.0.0-smithy-rs-head
    │       └── aws-http 0.0.0-smithy-rs-head
    │           └── aws-inlineable 0.0.0-smithy-rs-head
    ├── proptest 1.0.0
    └── aws-inlineable 0.0.0-smithy-rs-head

error: 1 vulnerability found!

(from rust-runtime)

Crate:     openssl
Version:   0.10.45
Title:     `openssl` `SubjectAlternativeName` and `ExtendedKeyUsage::other` allow arbitrary file read
Date:      2023-03-24
ID:        RUSTSEC-2023-0023
URL:       https://rustsec.org/advisories/RUSTSEC-2023-0023
Solution:  Upgrade to >=0.10.48
Dependency tree:
openssl 0.10.45
└── native-tls 0.2.11
    ├── tokio-native-tls 0.3.0
    │   └── hyper-tls 0.5.0
    │       └── aws-smithy-client 0.0.0-smithy-rs-head
    └── hyper-tls 0.5.0

Crate:     openssl
Version:   0.10.45
Title:     `openssl` `X509NameBuilder::build` returned object is not thread safe
Date:      2023-03-24
ID:        RUSTSEC-2023-0022
URL:       https://rustsec.org/advisories/RUSTSEC-2023-0022
Solution:  Upgrade to >=0.10.48

Crate:     openssl
Version:   0.10.45
Title:     `openssl` `X509Extension::new` and `X509Extension::new_nid` null pointer dereference
Date:      2023-03-24
ID:        RUSTSEC-2023-0024
URL:       https://rustsec.org/advisories/RUSTSEC-2023-0024
Solution:  Upgrade to >=0.10.48

Crate:     remove_dir_all
Version:   0.5.3
Title:     Race Condition Enabling Link Following and Time-of-check Time-of-use (TOCTOU)
Date:      2023-02-24
ID:        RUSTSEC-2023-0018
URL:       https://rustsec.org/advisories/RUSTSEC-2023-0018
Solution:  Upgrade to >=0.8.0
Dependency tree:

error: 4 vulnerabilities found!

These need to be fixed.

On top of that, we need to add a non-blocking CI action to check for vulnerabilities (the check only runs in aws-sdk-rust today so vulnerabilities won't get caught until later).

[jdisanti]

I believe this was fixed.