Bump shard count for f32_igemm_minmax_test (timing out on coverage runs)

PiperOrigin-RevId: 422634618
diff --git a/BUILD.bazel b/BUILD.bazel
index db798f6..b35381b 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -10873,6 +10873,7 @@
         "test/f32-igemm-minmax.cc",
         "test/f32-igemm-minmax-2.cc",
     ] + WEIGHTS_PACK_HDRS + MICROKERNEL_TEST_HDRS,
+    shard_count = 5,
     deps = MICROKERNEL_TEST_DEPS + [
         ":jit_test_mode",
         ":gemm_microkernel_tester",