Revert "CI: Pin VTest to a known good commit"

The issue with VTest now is fixed in VTest master since commit
vtest/VTest@040bb6737a6bd6c1f8941bc65ab8f3fc52d71130.

This reverts commit 24105300b87b5cfc1f21fd0788a0865723b043c8.
diff --git a/.github/workflows/vtest.yml b/.github/workflows/vtest.yml
index f5f35a6..6d42db8 100644
--- a/.github/workflows/vtest.yml
+++ b/.github/workflows/vtest.yml
@@ -60,7 +60,7 @@
         brew install lua
     - name: Install VTest
       run: |
-        curl -fsSL https://github.com/vtest/VTest/archive/02a9bc16d78e70d1d415b40d5349b9f3e56df05b.tar.gz -o VTest.tar.gz
+        curl -fsSL https://github.com/vtest/VTest/archive/master.tar.gz -o VTest.tar.gz
         mkdir VTest
         tar xvf VTest.tar.gz -C VTest --strip-components=1
         make -C VTest -j$(nproc) FLAGS="-O2 -s -Wall"