Fix regex

Author: eb-rubenespinosa

README.md

@@ -11,13 +11,19 @@ SEMVER validator
 ## Example usage
 
 ```yaml
-uses: actions/semver-validation-action@master
+uses: actions/semver-validation-action@0.0.5
 with:
   version: ${{ github.event.release.tag_name }}
 ```
 
 ```yaml
-uses: actions/semver-validation-action@master
+uses: actions/semver-validation-action@0.0.5
+with:
+  version: 'v0.7.9'
+```
+
+```yaml
+uses: actions/semver-validation-action@0.0.5
 with:
   version: '0.7.9-beta.1'
 ```

index.js

@@ -6,7 +6,7 @@ try {
   const version = core.getInput('version');
   console.log(`Checking version: ${version}!`);
 
-  var re = new RegExp("[0-9]+\.[0-9]+\.[0-9]+(-(0|[1-9]\d*|(beta|alpha).*))?$");
+  var re = new RegExp("(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(-(([a-z-][\da-z-]+|[\da-z-]+[a-z-][\da-z-]*|0|[1-9]\d*)(\.([a-z-][\da-z-]+|[\da-z-]+[a-z-][\da-z-]*|0|[1-9]\d*))*))?(\\+([\da-z-]+(\.[\da-z-]+)*))?$");
   if (re.exec(version) == null) {
     core.setFailed("Invalid version");
   }