Add support for beta versions in go.mod toolchain directive

__tests__/setup-go.test.ts

@@ -1237,7 +1237,7 @@ use .
   });
 
   describe('go-version-file-toolchain', () => {
-    const goVersions = ['1.22.0', '1.21rc2', '1.18'];
+    const goVersions = ['1.22.0', '1.21rc2', '1.18', '1.18beta2'];
     const placeholderVersion = '1.19';
     const buildGoMod = (
       goVersion: string,

dist/setup/index.js

@@ -42367,7 +42367,7 @@ function parseGoVersionFile(versionFilePath) {
         // 'GOTOOLCHAIN' has been explicitly set
         if (process.env[GOTOOLCHAIN_ENV_VAR] !== GOTOOLCHAIN_LOCAL_VAL) {
             // toolchain directive: https://go.dev/ref/mod#go-mod-file-toolchain
-            const matchToolchain = contents.match(/^toolchain go(1\.\d+(?:\.\d+|rc\d+)?)/m);
+            const matchToolchain = contents.match(/^toolchain go(1\.\d+(?:\.\d+|(beta|rc)\d+)?)/m);
             if (matchToolchain) {
                 return matchToolchain[1];
             }

src/installer.ts

@@ -657,7 +657,7 @@ export function parseGoVersionFile(versionFilePath: string): string {
     if (process.env[GOTOOLCHAIN_ENV_VAR] !== GOTOOLCHAIN_LOCAL_VAL) {
       // toolchain directive: https://go.dev/ref/mod#go-mod-file-toolchain
       const matchToolchain = contents.match(
-        /^toolchain go(1\.\d+(?:\.\d+|rc\d+)?)/m
+        /^toolchain go(1\.\d+(?:\.\d+|(beta|rc)\d+)?)/m
       );
       if (matchToolchain) {
         return matchToolchain[1];