feat: Update Emacs to version 28.1

Fixes #782.

Author: Kaushal.Modi

Dockerfile

@@ -35,6 +35,7 @@ RUN export DEBIAN_FRONTEND=noninteractive && \
     update-locale en_US.UTF-8 && \
     add-apt-repository -y ppa:ondrej/php && \
     add-apt-repository -y ppa:git-core/ppa && \
+    add-apt-repository -y ppa:kelleyk/emacs && \
     apt-get -y update && \
     apt-get install -y --no-install-recommends \
         advancecomp \
@@ -47,7 +48,7 @@ RUN export DEBIAN_FRONTEND=noninteractive && \
         cmake \
         doxygen \
         elixir \
-        emacs-nox \
+        emacs28-nox \
         expect \
         file \
         fontconfig \

included_software.md

@@ -27,7 +27,7 @@ The specific patch versions included will depend on when the image was last buil
 * Java
   * 8 (default)
 * Emacs
-  * 26.3 (default)
+  * 28.1 (default)
 * Erlang
   * 22.2 (default)
 * Elixir