Add assetRegex option

At some point in the recent past, I started getting installation errors when using this Feature:

```
nanolayer.installers.gh_release.resolvers.asset_resolver.AssetResolver.AssetResolverError: Too many matches found
```

The shellcheck v0.11.0 release added some assets a few weeks ago, which _could_ be the trigger that caused the above error:

https://github.com/koalaman/shellcheck/releases/tag/v0.11.0

I've added a pretty basic regex filter on the asset name that should limits the matches to gzipped tar files. If there's a more appropriate regex to use, please let me know.

I successfully tested this pattern locally by using the gh-release feature with the following configuration:

```json
"ghcr.io/devcontainers-extra/features/gh-release:1": {
  "repo": "koalaman/shellcheck",
  "binaryNames": "shellcheck",
  "assetRegex": "shellcheck-.*.tar.gz$"
},
```

Signed-off-by: Jason Garber <[email protected]>

Author: jgarber623

src/shellcheck/install.sh

@@ -16,6 +16,6 @@ $nanolayer_location \
     install \
     devcontainer-feature \
     "ghcr.io/devcontainers-extra/features/gh-release:1" \
-    --option repo='koalaman/shellcheck' --option binaryNames='shellcheck' --option version="$VERSION"
+    --option repo='koalaman/shellcheck' --option binaryNames='shellcheck' --option version="$VERSION" --option assetRegex='shellcheck-.*.tar.gz$'
 
 echo 'Done!'