adding cache for .genaiscript

.github/workflows/genai-pr-describe.yml

@@ -26,6 +26,11 @@ jobs:
                   node-version: "20"
                   cache: yarn
             - run: yarn install --frozen-lockfile
+            - name: cache .genaiscript
+              uses: actions/cache@v4
+              with:
+                  path: .genaiscript
+                  key: genaiscript-${{ hashFiles('**/yarn.lock') }}
             - name: compile
               run: yarn compile
             - name: git stuff