Fix flex release URL

Match https://github.com/hdl/bazel_rules_hdl/pull/297

Change-Id: I14a7a81cf21b24d35c831d5d70da65828514ec33
diff --git a/external/0006-Update-flex-release-URL.patch b/external/0006-Update-flex-release-URL.patch
new file mode 100644
index 0000000..0c363ec
--- /dev/null
+++ b/external/0006-Update-flex-release-URL.patch
@@ -0,0 +1,24 @@
+From 829fc85690342da860948372a023a54a558b56d5 Mon Sep 17 00:00:00 2001
+From: Cindy Liu <hcindyl@google.com>
+Date: Tue, 12 Mar 2024 18:56:36 -0700
+Subject: [PATCH] Update flex release URL
+
+---
+ .../com_github_westes_flex/com_github_westes_flex.bzl           | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git dependency_support/com_github_westes_flex/com_github_westes_flex.bzl dependency_support/com_github_westes_flex/com_github_westes_flex.bzl
+index 3a13bed..48c78f0 100644
+--- dependency_support/com_github_westes_flex/com_github_westes_flex.bzl
++++ dependency_support/com_github_westes_flex/com_github_westes_flex.bzl
+@@ -22,7 +22,7 @@ def com_github_westes_flex():
+         http_archive,
+         name = "com_github_westes_flex",
+         urls = [
+-            "https://github.com/westes/flex/files/981163/flex-2.6.4.tar.gz",
++            "https://github.com/westes/flex/releases/download/v2.6.4/flex-2.6.4.tar.gz",
+         ],
+         strip_prefix = "flex-2.6.4",
+         sha256 = "e87aae032bf07c26f85ac0ed3250998c37621d95f8bd748b31f15b33c45ee995",
+--
+2.44.0.278.ge034bb2e1d-goog
diff --git a/rules/repos.bzl b/rules/repos.bzl
index 6a70d75..e49c071 100644
--- a/rules/repos.bzl
+++ b/rules/repos.bzl
@@ -39,6 +39,7 @@
             "@kelvin_hw//external:0002-SystemC-support-for-verilator.patch",
             "@kelvin_hw//external:0003-Add-systemc-lib-support.patch",
             "@kelvin_hw//external:0004-Build-verilator-v4.226.patch",
+            "@kelvin_hw//external:0006-Update-flex-release-URL.patch",
         ],
     )