Add DNSPod support

[dongshuzhao]

resolve #98

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• I have read the contributing guideline and understand that I have made the correct modifications

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Description:

Benefits of this PR and context:

Added DNSPod support for swag-docker.
DNSPod is one of the most popular DNS service providers in China.

Initial issue: #98

How Has This Been Tested?

Test on my own home server with my own domain and DNSPod account.
DNS-01 challenge is smooth and certificates are properly issued.

Environment:
Docker 20.10.5

Testing log:

Source / References:

certpod-dns-dnspod: https://github.com/SkyLothar/certbot-dns-dnspod

[github-actions]

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[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://ci-tests.linuxserver.io/lspipepr/swag/1.21.0-pkg-fecd8d80-pr-181/index.html
https://ci-tests.linuxserver.io/lspipepr/swag/1.21.0-pkg-fecd8d80-pr-181/shellcheck-result.xml

[aptalca]

Upstream docs suggest the use of dns_dnspod_api_id but you PRed dns_dnspod_email. Was that an error?

[dongshuzhao]

Upstream docs suggest the use of dns_dnspod_api_id but you PRed dns_dnspod_email. Was that an error?

Sorry I was quoting a wrong fork of certbot-dns-dnspod plugin. The one in pip is maintained by SkyLothar (https://github.com/SkyLothar/certbot-dns-dnspod), which can be checked at https://pypi.org/project/certbot-dns-dnspod/ .
Fixed the comments in the conf file. The code was working correctly though.

Thanks for your reminder.

[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://ci-tests.linuxserver.io/lspipepr/swag/1.21.0-pkg-fecd8d80-pr-181/index.html
https://ci-tests.linuxserver.io/lspipepr/swag/1.21.0-pkg-fecd8d80-pr-181/shellcheck-result.xml

[LinuxServer-CI]

I am a bot, here are the test results for this PR:
https://ci-tests.linuxserver.io/lspipepr/swag/1.21.0-pkg-dae7f71c-pr-181/index.html
https://ci-tests.linuxserver.io/lspipepr/swag/1.21.0-pkg-dae7f71c-pr-181/shellcheck-result.xml