perf: unshallow with a filter

when action runs, unshallow the repository with filter `blob:none`.

this should makes git only download commits histories from the server without
loading file contents.

should make the action faster when running with large repository

src/git.ts

@@ -39,6 +39,6 @@ export async function revParse(rev: string, cwd?: string): Promise<string> {
   return output.trim()
 }
 
-export async function unshallow(): Promise<number> {
-  return exec('git', ['fetch', '--prune', '--unshallow'])
+export async function unshallowHistories(): Promise<number> {
+  return exec('git', ['fetch', '--prune', '--unshallow', '--filter=blob:none'])
 }

src/main.ts

@@ -1,6 +1,6 @@
 import * as core from '@actions/core'
 import {Rule, parseRules} from './rule'
-import {getChangedFiles, revParse, unshallow} from './git'
+import {getChangedFiles, revParse, unshallowHistories} from './git'
 import {newGlobber} from './glob'
 function evaluateRule(rule: Rule, changedFiles: string[]): string[] {
   const globber = newGlobber(rule.match)
@@ -25,7 +25,7 @@ async function getHeadSha(): Promise<string> {
 async function run(): Promise<void> {
   try {
     const event = core.getInput('event')
-    await unshallow()
+    await unshallowHistories()
     const baseSha = await getBaseSha(event)
     const headSha = await getHeadSha()
     core.debug(`baseSha: ${baseSha}`)