Pinned the version of Meson to use in Ubuntu 16.04.

Author: UncombedCoconut

CHANGELOG.md

@@ -1,3 +1,6 @@
+### v1.3.2:
+Pinned the version of Meson to use in Ubuntu 16.04. This situation is temporary; 16.04 will stop being the base system for AppImage builds by late April. Refs: <https://packages.ubuntu.com/source/xenial-backports/ninja-build> <https://docs.appimage.org/reference/best-practices.html#binaries-compiled-on-old-enough-base-system>
+
 ### v1.3.1:
 Added MXE packaged luajit to naev-windows image.
 Returned to official Meson releases in the naev-macos image, now that a key bug-fix is released.

naev/naev-ubuntu1604/Dockerfile

@@ -34,7 +34,8 @@ RUN update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.9 1
 RUN python3 -m pip install mutagen
 
 # Install meson via pip.
-RUN python3 -m pip install meson && \
+# The 0.57 release requires ninja-build >=1.8.2
+RUN python3 -m pip install meson==0.56 && \
     echo "Verifying meson install" && \
     which meson && \
     meson --version