fixup some inconsistent casing in dockerfile

Author: jorgen

docker/ubuntu24.04/Dockerfile

@@ -24,5 +24,5 @@ RUN git clone --depth=1 https://github.com/llvm/llvm-project && \
     ninja -C build cxx cxxabi && \
     ninja -C build install-cxx install-cxxabi
 
-env MSAN_CFLAGS="-std=c++20 -fsanitize=memory -nostdinc++ -I/opt/include -I/opt/include/c++/v1"
-env MSAN_LFLAGS="-fsanitize=memory -stdlib=libc++ -L/opt/lib -lc++abi -Wl,-rpath,/opt/lib"
+ENV MSAN_CFLAGS="-std=c++20 -fsanitize=memory -nostdinc++ -I/opt/include -I/opt/include/c++/v1"
+ENV MSAN_LFLAGS="-fsanitize=memory -stdlib=libc++ -L/opt/lib -lc++abi -Wl,-rpath,/opt/lib"