rust: Only include required files in crate tarballs

… that are uploaded to crates.io.

cargo-diet output for this change:

┌────────────────────────────────────────────────────────────────┬─────────────┐
│ Removed File                                                   │ Size (Byte) │
├────────────────────────────────────────────────────────────────┼─────────────┤
│ tests/it/utils/mod.rs                                          │          21 │
│ .rustfmt.toml                                                  │          51 │
│ tests/it/main.rs                                               │          53 │
│ .gitignore                                                     │          53 │
│ templates/api_summary.rs.jinja                                 │         593 │
│ templates/component_type.rs.jinja                              │         602 │
│ templates/api_extra/application_create.rs                      │         619 │
│ templates/types/integer_enum.rs.jinja                          │         667 │
│ templates/types/string_enum.rs.jinja                           │         786 │
│ tests/it/mode_serialization.rs                                 │        1018 │
│ templates/api_extra/message.rs                                 │        1097 │
│ .openapi-generator-ignore                                      │        1150 │
│ templates/types/struct_enum.rs.jinja                           │        1303 │
│ tests/it/utils/test_client.rs                                  │        1327 │
│ templates/api_extra/message_attempt_list_attempted_messages.rs │        1338 │
│ templates/types/struct.rs.jinja                                │        1561 │
│ templates/api_extra/message_expunge_content.rs                 │        1658 │
│ templates/types/struct_fields.rs.jinja                         │        1748 │
│ templates/api_resource.rs.jinja                                │        5101 │
│ tests/it/kitchen_sink.rs                                       │        6546 │
└────────────────────────────────────────────────────────────────┴─────────────┘
Saved 13% or 27.3 KB in 20 files (of 211.1 KB and 120 files in entire crate)

rust/Cargo.toml

@@ -10,6 +10,7 @@ readme = "../README.md"
 license = "MIT"
 keywords = ["svix", "webhooks", "diahook"]
 categories = ["development-tools", "asynchronous", "network-programming", "web-programming"]
+include = ["src/**/*", "README.md"]
 
 [features]
 # openssl-sys keeps showing up in the CLI dep graph, breaking the build, even when