nuttx-ci-linux: Install libpython2.7 for xtensa-esp32-elf-gdb (again)

This time to the correct apt-get line.

root@5b2362eb60c2:/src/nuttx# ldd /tools/xtensa-esp32-elf-gcc/bin/xtensa-esp32-elf-gdb
        linux-vdso.so.1 (0x00007ffeb59f3000)
        libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f2a7fc31000)
        libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f2a7fc0e000)
        libutil.so.1 => /lib/x86_64-linux-gnu/libutil.so.1 (0x00007f2a7fc09000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f2a7faba000)
        libpython2.7.so.1.0 => /lib/x86_64-linux-gnu/libpython2.7.so.1.0 (0x00007f2a7f74e000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f2a7f55c000)
        /lib64/ld-linux-x86-64.so.2 (0x00007f2a7fc3f000)
        libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f2a7f53e000)
root@5b2362eb60c2:/src/nuttx#
diff --git a/docker/linux/Dockerfile b/docker/linux/Dockerfile
index 622b860..90c844e 100644
--- a/docker/linux/Dockerfile
+++ b/docker/linux/Dockerfile
@@ -213,6 +213,7 @@
 
 RUN dpkg --add-architecture i386
 # This is used for the final images so make sure to not store apt cache
+# Note: xtensa-esp32-elf-gdb is linked to libpython2.7
 RUN apt-get update -qq && DEBIAN_FRONTEND="noninteractive" apt-get install -y -qq --no-install-recommends \
   -o APT::Immediate-Configure=0 \
   avr-libc \
@@ -229,6 +230,7 @@
   libasound2-dev libasound2-dev:i386 \
   libcurl4-openssl-dev \
   libpulse-dev libpulse-dev:i386 \
+  libpython2.7 \
   libx11-dev libx11-dev:i386 \
   libxext-dev libxext-dev:i386 \
   linux-libc-dev:i386 \