http_utility: removed unused using

GCC 15.1 fails with the following:

```
19:18:43 | ../git/include/http_utility.hpp:50:30: error: unused using-declaration 'boost::spirit::x3::uint_' [-Werror=unused-variable]
19:18:43 |    50 |     using boost::spirit::x3::uint_;
```

Fix it with a trivial removal of an unused using.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ia24038d3146e818062dfb3f6c0c6bc84fa1ba470
diff --git a/include/http_utility.hpp b/include/http_utility.hpp
index ce5f23e..9768526 100644
--- a/include/http_utility.hpp
+++ b/include/http_utility.hpp
@@ -47,7 +47,6 @@
     using boost::spirit::x3::parse;
     using boost::spirit::x3::space;
     using boost::spirit::x3::symbols;
-    using boost::spirit::x3::uint_;
 
     const symbols<ContentType> knownMimeType{
         {"application/cbor", ContentType::CBOR},
@@ -86,7 +85,6 @@
     using boost::spirit::x3::parse;
     using boost::spirit::x3::space;
     using boost::spirit::x3::symbols;
-    using boost::spirit::x3::uint_;
 
     const symbols<ContentType> knownMimeType{
         {"application/cbor", ContentType::CBOR},