Upgrade TS to 0.21.0

This is the minimal version I could find that fits all criteria:

1. Determinstic output: tree-sitter/tree-sitter#2755
2. Published for ARM64
3. Tests for reprolang pass

.github/workflows/protobuf-reprolang.yml

@@ -28,7 +28,8 @@ jobs:
 
       - run: docker pull ghcr.io/sourcegraph/scip:latest || echo "no suitable cache"
 
-      - run: |
+      - name: Regenerate protobuf bindings and reprolang parser
+        run: |
           # We're changing the owner of the checkout folder to a particular user id,
           # matching the user id of `asdf` user we create inside the docker container.
           sudo chown -R 1001:1001 . && ./dev/generate-all-in-docker.sh

cmd/scip/tests/reprolang/package.json

@@ -12,6 +12,6 @@
     "nan": "^2.15.0"
   },
   "devDependencies": {
-    "tree-sitter-cli": "^0.20.8"
+    "tree-sitter-cli": "0.21.0"
   }
 }