fix: build.rs docs build

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name        = "phnt"
-version     = "0.0.20"
+version     = "0.0.21"
 license     = "MIT"
 authors     = ["oberrich <[email protected]>"]
 repository  = "https://github.com/oberrich/phnt-rs"

src/build.rs

@@ -1,5 +1,29 @@
+// MIT License
+//
+// Copyright (c) 2024 oberrich <[email protected]>
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+//
+#![cfg_attr(docsrs, feature(doc_cfg))]
 use std::collections::HashMap;
 use std::env;
+#[cfg(all(not(feature = "vendored"), not(docsrs)))]
 use std::path::PathBuf;
 
 use regex::Regex;