Merge bitcoindevkit/bdk#1391: Fix cargo manifest for bdk_testenv

25800139124a37608c9da0a6ad76c22795f110d6 chore(testenv): fix cargo manifest (志宇)

Pull request description:

  ### Description

  This will make the `bdk_testenv` crate actually publishable.

  ### Changelog notice

  * Fix cargo manifest of `bdk_testenv`.

  ### Checklists

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)
  * [x] I ran `cargo fmt` and `cargo clippy` before committing

ACKs for top commit:
  LLFourn:
    ACK 25800139124a37608c9da0a6ad76c22795f110d6

Tree-SHA512: 52707450473713490cb1115af06747dc4d6f78cf4bf877cd3a246064af11786b5a89829731e911ffba19a71db9b19a60ad5b12f20871d57b296427761707d826

crates/testenv/Cargo.toml

@@ -2,6 +2,13 @@
 name = "bdk_testenv"
 version = "0.1.0"
 edition = "2021"
+rust-version = "1.63"
+homepage = "https://bitcoindevkit.org"
+repository = "https://github.com/bitcoindevkit/bdk"
+documentation = "https://docs.rs/bdk_testenv"
+description = "Testing framework for BDK chain sources."
+license = "MIT OR Apache-2.0"
+readme = "README.md"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
@@ -14,4 +21,4 @@ anyhow = { version = "1" }
 [features]
 default = ["std"]
 std = ["bdk_chain/std"]
-serde = ["bdk_chain/serde"]
+serde = ["bdk_chain/serde"]