fix: version resolution when only version file is present

Signed-off-by: Frost Ming <me@frostming.com>

action.yml

@@ -5,8 +5,6 @@ author: Frost Ming
 inputs:
   python-version:
     description: 'Version range or exact version of a Python version to use, using SemVer''s version range syntax.'
-    default: 3.x
-    required: false
   python-version-file:
     description: 'File containing the Python version to use. Example: .python-version'
   architecture:

dist/setup-pdm.js

@@ -91003,7 +91003,7 @@ function isCacheAvailable() {
 }
 function resolveVersionInputFromDefaultFile() {
   const couples = [
-    [".python-version", getVersionInputFromPlainFile]
+    ["pyproject.toml", getVersionInputFromTomlFile]
   ];
   for (const [versionFile, _fn] of couples) {
     logWarning(

package.json

@@ -1,6 +1,6 @@
 {
   "name": "setup-pdm",
-  "version": "2.0.0",
+  "version": "4.0.0",
   "packageManager": "pnpm@8.14.3",
   "description": "The GitHub Action for using pdm as the package manager",
   "repository": {

src/utils.ts

@@ -7,7 +7,7 @@ import { useCpythonVersion } from 'setup-python/src/find-python'
 import { findPyPyVersion } from 'setup-python/src/find-pypy'
 import {
   getVersionInputFromFile,
-  getVersionInputFromPlainFile,
+  getVersionInputFromTomlFile,
   logWarning,
 } from 'setup-python/src/utils'
 import { getExecOutput } from '@actions/exec'
@@ -80,7 +80,7 @@ export function isCacheAvailable(): boolean {
 
 function resolveVersionInputFromDefaultFile(): string[] {
   const couples: [string, (versionFile: string) => string[]][] = [
-    ['.python-version', getVersionInputFromPlainFile],
+    ['pyproject.toml', getVersionInputFromTomlFile],
   ]
   for (const [versionFile, _fn] of couples) {
     logWarning(