Cache python installs (#621)

This pull request introduces support for caching Python installs in the
GitHub Action, allowing users to cache not only dependencies but also
the Python interpreter itself.

This works by setting the `UV_PYTHON_INSTALL_DIR` to a subdirectory of
the dependency cache path so that Python installs are directed there.

Fixes #135

---------

Co-authored-by: Kevin Stillhammer <kevin.stillhammer@gmail.com>

src/cache/restore-cache.ts

@@ -5,7 +5,9 @@ import { hashFiles } from "../hash/hash-files";
 import {
   cacheDependencyGlob,
   cacheLocalPath,
+  cachePython,
   cacheSuffix,
+  getUvPythonDir,
   pruneCache,
   pythonVersion as pythonVersionInput,
   restoreCache as shouldRestoreCache,
@@ -30,8 +32,12 @@ export async function restoreCache(): Promise<void> {
   core.info(
     `Trying to restore uv cache from GitHub Actions cache with key: ${cacheKey}`,
   );
+  const cachePaths = [cacheLocalPath];
+  if (cachePython) {
+    cachePaths.push(await getUvPythonDir());
+  }
   try {
-    matchedKey = await cache.restoreCache([cacheLocalPath], cacheKey);
+    matchedKey = await cache.restoreCache(cachePaths, cacheKey);
   } catch (err) {
     const message = (err as Error).message;
     core.warning(message);
@@ -62,7 +68,8 @@ async function computeKeys(): Promise<string> {
   const pythonVersion = await getPythonVersion();
   const platform = await getPlatform();
   const pruned = pruneCache ? "-pruned" : "";
-  return `setup-uv-${CACHE_VERSION}-${getArch()}-${platform}-${pythonVersion}${pruned}${cacheDependencyPathHash}${suffix}`;
+  const python = cachePython ? "-py" : "";
+  return `setup-uv-${CACHE_VERSION}-${getArch()}-${platform}-${pythonVersion}${pruned}${python}${cacheDependencyPathHash}${suffix}`;
 }
 
 async function getPythonVersion(): Promise<string> {