build: fix workflow access to git history

Refs: https://github.com/nodejs/node/pull/41466

PR-URL: https://github.com/nodejs/node/pull/41472
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Tierney Cyren <hello@bnb.im>

.github/workflows/find-inactive-tsc.yml

@@ -19,6 +19,7 @@ jobs:
       - name: Checkout the repo
         uses: actions/checkout@v2
         with:
+          fetch-depth: 0
           persist-credentials: false
 
       - name: Clone nodejs/TSC repository

tools/find-inactive-tsc.mjs

@@ -211,7 +211,8 @@ async function moveTscToEmeritus(peopleToMove) {
 // only been on the TSC for a week and therefore hasn't attended any meetings.
 const tscMembersAtEnd = await getTscFromReadme();
 
-await runGitCommand(`git checkout 'HEAD@{${SINCE}}' -- README.md`);
+const startCommit = await runGitCommand(`git rev-list -1 --before '${SINCE}' HEAD`);
+await runGitCommand(`git checkout ${startCommit} -- README.md`);
 const tscMembersAtStart = await getTscFromReadme();
 await runGitCommand('git reset HEAD README.md');
 await runGitCommand('git checkout -- README.md');