ci: stop passing --enable-ubsan

It's just a follow-up to 5f40423 (where --enable-ubsan
was removed).

Signed-off-by: Evgeny Vereshchagin <evvers@ya.ru>

.github/workflows/build.yml

@@ -47,11 +47,7 @@ jobs:
           BUILD="$(pwd)/build"
           mkdir -p "${BUILD}"
           cd "${BUILD}"
-          if [ "${{ matrix.compiler }}" = "gcc" ]; then
-            ../configure --enable-tests --enable-ubsan --with-distro=unknown
-          else
-            ../configure --enable-tests --with-distro=unknown
-          fi
+          ../configure --enable-tests --with-distro=unknown
 
           # Build
           make -j4