Fix cache keys for Python version ranges (#937)

## Summary
- URL-encode the Python version component before adding it to the cache
key
- URL-encode the user-provided cache suffix for the same reason
- Add cache key tests for Python ranges, comma-containing suffixes, and
unchanged simple inputs

Fixes #914

Refs: pi-session 019f3164-85e7-7817-bffd-501d89b3a1fd

## Tests
- npm run all

__tests__/helpers/setup-inputs.ts

@@ -0,0 +1,36 @@
+import { CacheLocalSource, type SetupInputs } from "../../src/utils/inputs";
+
+export function createSetupInputs(
+  overrides: Partial<SetupInputs> = {},
+): SetupInputs {
+  return {
+    activateEnvironment: false,
+    addProblemMatchers: false,
+    cacheDependencyGlob: "uv.lock",
+    cacheLocalPath: {
+      path: "/tmp/setup-uv-cache",
+      source: CacheLocalSource.Input,
+    },
+    cachePython: false,
+    cacheSuffix: "",
+    checksum: "",
+    downloadFromAstralMirror: false,
+    enableCache: true,
+    githubToken: "",
+    ignoreEmptyWorkdir: false,
+    ignoreNothingToCache: false,
+    noProject: false,
+    pruneCache: true,
+    pythonDir: "/tmp/uv-python-dir",
+    pythonVersion: "",
+    quiet: false,
+    resolutionStrategy: "highest",
+    restoreCache: false,
+    saveCache: true,
+    venvPath: "/workspace/.venv",
+    version: "",
+    versionFile: "",
+    workingDirectory: "/workspace",
+    ...overrides,
+  };
+}