Merge #2099: Fix no-std compilation

546b07e chore(example_cli,esplora): Fix no-std compilation (志宇)

Pull request description:

  ### Description

  `serde_json` requires either `std` or `alloc` feature enabled. We just enable `alloc` as we don't need the features that `std` provides.

  ### Notes to the reviewers

  `alloc` is just a subset of `std`. `json_serde` has `from_reader()` & `to_writer()` methods if `std` is enabled. We aren't using those methods so just having `alloc` is fine.

  I'm also not sure why an explicit `alloc` cargo feature flag is needed in `serde_json`. They can just have an internal prelude based on whether the `std` feature is enabled.

  ### Checklists

  #### All Submissions:

  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk/blob/master/CONTRIBUTING.md)

ACKs for top commit:
  luisschwab:
    ACK 546b07e
  oleonardolima:
    ACK 546b07e

Tree-SHA512: 05afc4d7ee3c1c7de8f2cd497a6a02f7bc4f1410e83604627c8af2b1a36fb92cd2fbe774a8d63bf2c4cffc8d4ddcc009adfdaeb59cdca3201f128f34639f39c2

Author: oleonardolima

crates/esplora/Cargo.toml

@@ -20,6 +20,7 @@ bdk_core = { path = "../core", version = "0.6.1", default-features = false }
 esplora-client = { version = "0.12.1", default-features = false }
 async-trait = { version = "0.1.66", optional = true }
 futures = { version = "0.3.26", optional = true }
+serde_json = { version = "1.0", features = ["alloc"] }
 
 [dev-dependencies]
 esplora-client = { version = "0.12.0" }

examples/example_cli/Cargo.toml

@@ -15,4 +15,4 @@ anyhow = "1"
 clap = { version = "4.5.17", features = ["derive", "env"] }
 rand = "0.8"
 serde = { version = "1", features = ["derive"] }
-serde_json = "1.0"
+serde_json = { version = "1.0", features = ["alloc"] }