Move the daily release compat date 7 days into the future

[penalosa]

Fixes #6008

[kentonv]

IMO we should also adjust the validation code to still enforce that the date can't be newer than today.

diff --git a/src/workerd/io/compatibility-date.c++ b/src/workerd/io/compatibility-date.c++
index be2ec8b4f..6db121f05 100644
--- a/src/workerd/io/compatibility-date.c++
+++ b/src/workerd/io/compatibility-date.c++
@@ -115,6 +115,16 @@ static void compileCompatibilityFlags(kj::StringPtr compatDate,
                 "date supported by this server binary is \"",
                 SUPPORTED_COMPATIBILITY_DATE, "\"."));
       }
+
+      // workerd is built with SUPPORTED_COMPATIBILITY_DATE set a little bit into the futurue, so
+      // that the build can support setting the compat date to today until the next release is
+      // ready. But we don't want people to actually set their compat date in the future, so let's
+      // check against the clock time as well.
+      if (CompatDate::today() < parsedCompatDate) {
+        errorReporter.addError(
+            kj::str("Can't set compatibility date in the future: ", parsedCompatDate));
+      }
+
       break;
 
     case CompatibilityDateValidation::CURRENT_DATE_FOR_CLOUDFLARE:

[MattieTK]

We should do a changelog on this or some other kind of comms. New docs and link to them as part of the error message. Happy to help do that.

[vicb]

@penalosa Looks like this test needs to be updated