Moved VITASDK back to env vars on action

.github/workflows/build-helloworld-vita.yml

@@ -5,6 +5,9 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
+    env:
+      VITASDK: /usr/local/vitasdk
+      
     steps:
       - name: Checkout
         uses: actions/checkout@v3

ci/install-vita-toolchain.sh

@@ -3,6 +3,5 @@ sudo apt-get install cmake
 git clone https://github.com/vitasdk/vdpm ~/vdpm
 cd ~/vdpm
 ./bootstrap-vitasdk.sh
-export VITASDK=/usr/local/vitasdk
 export PATH=$VITASDK/bin:$PATH
 ./install-all.sh