remove comment about Mastodon

this was done in #1232

Signed-off-by: Chad Dougherty <[email protected]>

Author: Chad Dougherty

docs/tests_ci.md

@@ -185,10 +185,6 @@ Importantly, once you create the bot you'll need to add the following secrets to
 
 Yes, this means that the tokens are specific to this account.
 
-#### Post New Jobs to Mastadon
-
-TBD: we welcome contributions to make this happen
-
 #### Greetings
 
 This simple greetings action greets first-time users (for issues).