Add input version-file (#486)

Closes: #411

src/version/config-file.ts

@@ -0,0 +1,22 @@
+import fs from "node:fs";
+import * as toml from "smol-toml";
+
+export function getRequiredVersionFromConfigFile(
+  filePath: string,
+): string | undefined {
+  if (!filePath.endsWith(".toml")) {
+    return undefined;
+  }
+  const fileContent = fs.readFileSync(filePath, "utf-8");
+
+  if (filePath.endsWith("pyproject.toml")) {
+    const tomlContent = toml.parse(fileContent) as {
+      tool?: { uv?: { "required-version"?: string } };
+    };
+    return tomlContent?.tool?.uv?.["required-version"];
+  }
+  const tomlContent = toml.parse(fileContent) as {
+    "required-version"?: string;
+  };
+  return tomlContent["required-version"];
+}