include, tests: Address concerns from -Wsign-compare

After switching to Debian Trixie these surfaced as issues when building
locally.

Change-Id: I92a4d19579257e796aa29be8d4fb79fe92466780
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
diff --git a/tests/dsp/bios_table.cpp b/tests/dsp/bios_table.cpp
index bdef5a6..0186a44 100644
--- a/tests/dsp/bios_table.cpp
+++ b/tests/dsp/bios_table.cpp
@@ -1050,7 +1050,7 @@
     EXPECT_EQ(pldm_bios_table_string_entry_decode_string(
                   entry, buffer.data(), 2 + 1 /* sizeof '\0'*/),
               PLDM_SUCCESS);
-    EXPECT_EQ(strlen(buffer.data()), 2);
+    EXPECT_EQ(strlen(buffer.data()), 2ul);
     EXPECT_EQ(std::strcmp("Al", buffer.data()), 0);
 
     auto rc = pldm_bios_table_string_entry_decode_string(entry, buffer.data(),