fix: pass cwd to readChangesetState and runVersion

Fixes the issue where cwd parameter was not being passed to
readChangesetState() and runVersion(), causing the action to
fail in monorepos with nested workspaces.

This is a backport of PR changesets#536 from upstream.

Author: sharkey11

dist/index.js

@@ -43,7 +43,7 @@ const getOptionalInput = (name: string) => core.getInput(name) || undefined;
     `machine github.com\nlogin github-actions[bot]\npassword ${githubToken}`
   );
 
-  let { changesets } = await readChangesetState();
+  let { changesets } = await readChangesetState(cwd);
 
   let publishScript = core.getInput("publish");
   let hasChangesets = changesets.length !== 0;
@@ -122,6 +122,7 @@ const getOptionalInput = (name: string) => core.getInput(name) || undefined;
         script: getOptionalInput("version"),
         git,
         octokit,
+        cwd,
         prTitle: getOptionalInput("title"),
         commitMessage: getOptionalInput("commit"),
         hasPublishScript,