go.mod: bump to Go 1.24.4

and use this opportunity to bust the cache.
good to do every once in a while.
diff --git a/.github/workflows/go_test.yml b/.github/workflows/go_test.yml
index b250647..8ea2e03 100644
--- a/.github/workflows/go_test.yml
+++ b/.github/workflows/go_test.yml
@@ -25,14 +25,14 @@
           go-version-file: "go.mod"
           cache: true
 
-      - name: Cache Go 1.24.2
+      - name: Cache Go 1.24.4
         uses: actions/cache@v4
         with:
           path: |
             ~/.cache/go-build
-          key: ${{ runner.os }}-go1.24.2-${{ hashFiles('**/go.sum') }}
+          key: ${{ runner.os }}-go1.24.4-${{ hashFiles('**/go.sum') }}
           restore-keys: |
-            ${{ runner.os }}-go1.24.2-
+            ${{ runner.os }}-go1.24.4-
 
       - name: Install tools
         run: |