Upgrade Dockerfile language server to 0.7.3

[rcjsuen]

This update to the Dockerfile language server fixes three issues that have been raised by the community:

• the formatter will now ignore heredocs (Autoformatting breaks Dockerfile with heredoc #3327)
• the server will no longer enter an infinite loop when using Intellisense in ADD or COPY instructions (Dockerfile language server hangs #3347)
• errors will no longer be thrown when using Intellisense after a --chown or --from flag in ADD or COPY instructions (Language server errors whilst writing COPY --from line #3349)

FROM alpine as alpine
# invoke Intellisense at the end of COPY, the CPU usage of the
# Dockerfile language server should not jump to 99% (issue #3347)
COPY . . 

FROM node:alpine
# invoke Intellisense at the end of this ADD instruction,
# there should be no more errors (issue #3349)
ADD --chown=user:group
# invoke Intellisense at the end of this COPY instruction,
# there should be no more errors (issue #3349)
COPY --chown=user:group

# issue #3327
# 1. format the document, these three lines should not change
# 2. highlight and select the three lines and use format selection,
# the three lines should not change
# 3. add a backslash (\) after "cat", the EOT line should not move
RUN <<EOT
    cat
EOT

[rcjsuen]

I've contributed before but it looks like the build doesn't think so. Let me know if you all need me to do something different or whatever.

[bwateratmsft]

I've contributed before but it looks like the build doesn't think so. Let me know if you all need me to do something different or whatever.

Weird...oh well, I approved it to run. Maybe its memory only extends back to the point where we added this GitHub Action.

[bwateratmsft]

LGTM!

[rcjsuen]

@bwateratmsft Thanks for the review!

Is the team planning to cut a new release this month or next month?

[bwateratmsft]

Given the holidays and lots of people taking time off, we're planning to skip a month, so releasing tentatively 17 Jan.