Use the vergen crate to generate version information

* Add depend on the `vergen` crate (only use the `build`, `git` and
  `gitcl` features)
* Add the build script `build.rs` to setup the environment variables
  from the build system

Cargo.lock

@@ -17,6 +17,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "anyhow"
+version = "1.0.71"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c7d0618f0e0b7e8ff11427422b64564d5fb0be1940354bfe2e0529b18a9d9b8"
+
 [[package]]
 name = "approx"
 version = "0.5.1"
@@ -1847,6 +1853,7 @@ dependencies = [
  "reqwest",
  "rocket",
  "thiserror",
+ "vergen",
 ]
 
 [[package]]
@@ -2274,6 +2281,17 @@ version = "0.2.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "accd4ea62f7bb7a82fe23066fb0957d48ef677f6eeb8215f372f52e48bb32426"
 
+[[package]]
+name = "vergen"
+version = "8.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b3c89c2c7e50f33e4d35527e5bf9c11d6d132226dbbd1753f0fbe9f19ef88c6"
+dependencies = [
+ "anyhow",
+ "rustversion",
+ "time 0.3.20",
+]
+
 [[package]]
 name = "version_check"
 version = "0.9.4"

Cargo.toml

@@ -22,6 +22,9 @@ reqwest = { version = "0.11.9", features = ["json"] }
 rocket = { version = "0.5.0-rc.3", features = ["json"] }
 thiserror = "1.0.31"
 
+[build-dependencies]
+vergen = { version = "8.2.1", default-features = false, features = ["build", "git", "gitcl"] }
+
 [dev-dependencies]
 assert_float_eq = "1.1.3"
 assert_matches = "1.5.0"

build.rs

@@ -0,0 +1,9 @@
+use std::error::Error;
+use vergen::EmitBuilder;
+
+fn main() -> Result<(), Box<dyn Error>> {
+    // Generate the `cargo:` instructions to fill the appropriate environment variables.
+    EmitBuilder::builder().all_build().all_git().emit()?;
+
+    Ok(())
+}