Add revs update script

scripts/update-revs.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.."
+
+if ! git diff-index --quiet HEAD; then
+    echo "Not running update-revs.sh because git working directory is dirty" >&2
+    exit 1
+fi
+
+base=$(git rev-parse HEAD)
+git checkout --quiet "$base"
+
+for rev in 1.{0..60}.0 stable beta nightly; do
+    echo "Updating $rev branch"
+    git branch --quiet --delete --force $rev &>/dev/null || true
+    sed -i "s/required: true/required: false\n    default: $rev/" action.yml
+    git add action.yml
+    git commit --quiet --message "toolchain: $rev"
+    git checkout --quiet -b $rev
+    git checkout --quiet "$base"
+done