fix: pin ANTLR4 version in CI to avoid Maven Central version lookup failure

antlr4-tools queries Maven Central to discover the latest ANTLR4 version
on a cold cache. The API returns HTTP 400 on GitHub Actions runners, causing
make grammar to fail with FileNotFoundError.

Set ANTLR4_TOOLS_ANTLR_VERSION=4.13.2 in the Generate parser step so
antlr4-tools skips the version API call and downloads the JAR directly
from repo1.maven.org instead.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: ako

.github/workflows/nightly.yml

@@ -33,6 +33,8 @@ jobs:
         run: pip install 'antlr4-tools==0.2.2'
       - name: Generate parser
         run: make grammar
+        env:
+          ANTLR4_TOOLS_ANTLR_VERSION: '4.13.2'
       - name: Build
         run: make build
 
@@ -69,6 +71,8 @@ jobs:
         run: pip install 'antlr4-tools==0.2.2'
       - name: Generate parser
         run: make grammar
+        env:
+          ANTLR4_TOOLS_ANTLR_VERSION: '4.13.2'
 
       - name: Check for new commits since last nightly
         id: check

.github/workflows/push-test.yml

@@ -22,6 +22,8 @@ jobs:
         run: pip install 'antlr4-tools==0.2.2'
       - name: Generate parser
         run: make grammar
+        env:
+          ANTLR4_TOOLS_ANTLR_VERSION: '4.13.2'
       - name: Build
         run: make build
       - name: Test

.github/workflows/release.yml

@@ -28,6 +28,8 @@ jobs:
         run: pip install 'antlr4-tools==0.2.2'
       - name: Generate parser
         run: make grammar
+        env:
+          ANTLR4_TOOLS_ANTLR_VERSION: '4.13.2'
       - name: Build release binaries
         run: make release
       - name: Create GitHub Release