bpo-42208: GitHub Action: Add gdb to posix dependencies (GH-23043) (GH-23047)

Sort also dependencies and remove duplicates (liblzma-dev).
(cherry picked from commit 6e03c0a)

Co-authored-by: Victor Stinner <[email protected]>

Co-authored-by: Victor Stinner <[email protected]>

Author: miss-islington

.github/workflows/posix-deps-apt.sh

@@ -3,19 +3,19 @@ apt-get update
 
 apt-get -yq install \
     build-essential \
-    zlib1g-dev \
+    gdb \
+    lcov \
     libbz2-dev \
+    libffi-dev \
+    libgdbm-dev \
     liblzma-dev \
     libncurses5-dev \
     libreadline6-dev \
     libsqlite3-dev \
     libssl-dev \
-    libgdbm-dev \
-    tk-dev \
     lzma \
     lzma-dev \
-    liblzma-dev \
-    libffi-dev \
+    tk-dev \
     uuid-dev \
     xvfb \
-    lcov
+    zlib1g-dev