fix: Handle CMake 4.0+ compatibility for acarsdec build (#136)

CMake 4.0 removed backward compat with cmake_minimum_required < 3.5.
Add -DCMAKE_POLICY_VERSION_MINIMUM=3.5 to acarsdec cmake invocations
in setup.sh (macOS + Debian) and Dockerfile.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Dockerfile

@@ -137,7 +137,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     && git clone --depth 1 https://github.com/TLeconte/acarsdec.git \
     && cd acarsdec \
     && mkdir build && cd build \
-    && cmake .. -Drtl=ON \
+    && cmake .. -Drtl=ON -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
     && make \
     && cp acarsdec /usr/bin/acarsdec \
     && rm -rf /tmp/acarsdec \

setup.sh

@@ -616,6 +616,7 @@ install_acarsdec_from_source_macos() {
     info "Compiling acarsdec..."
     build_log="$tmp_dir/acarsdec-build.log"
     if cmake .. -Drtl=ON \
+         -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
          -DCMAKE_C_FLAGS="-I${HOMEBREW_PREFIX}/include" \
          -DCMAKE_EXE_LINKER_FLAGS="-L${HOMEBREW_PREFIX}/lib" \
          >"$build_log" 2>&1 \
@@ -1018,7 +1019,7 @@ install_acarsdec_from_source_debian() {
     mkdir -p build && cd build
 
     info "Compiling acarsdec..."
-    if cmake .. -Drtl=ON >/dev/null 2>&1 && make >/dev/null 2>&1; then
+    if cmake .. -Drtl=ON -DCMAKE_POLICY_VERSION_MINIMUM=3.5 >/dev/null 2>&1 && make >/dev/null 2>&1; then
       $SUDO install -m 0755 acarsdec /usr/local/bin/acarsdec
       ok "acarsdec installed successfully."
     else