minor #17320 [Mailer] Mailer: remove port 99 for requestbin.com (alexislefebvre)

This PR was merged into the 4.4 branch.

Discussion
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[Mailer] Mailer: remove port 99 for requestbin.com

It looked strange when there were 2 examples with different ports, why use duplicated lines since the value of the second line will overwrite the value of the first one?

I can't find any reference to port 99 in the documentation of requestbin.com, so I suggest to keep only one example.

Commits
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6008587 Mailer: remove port 99 for requestbin.com

Author: javiereguiluz

mailer.rst

@@ -174,7 +174,6 @@ Sendgrid             sendgrid+smtp://KEY@default                n/a
 
         # .env
         MAILER_DSN=mailgun+https://KEY:DOMAIN@requestbin.com
-        MAILER_DSN=mailgun+https://KEY:DOMAIN@requestbin.com:99
 
     Note that the protocol is *always* HTTPs and cannot be changed.