Merge rust-bitcoin/rust-bitcoin#1791: ci: Check for remaining NEXT_RELEASE in the release script

b3b57518a0 ci: Check for remaining NEXT_RELEASE in the release script (Steven Roose)

Pull request description:

  The intention here is that we can use the deprecation tag
  `#[deprecated(since = "NEXT_RELEASE")]` and fill in the version number
  at release time.

  Not sure if there is a good place to mention this somewhere in developer docs. I looked into CONTRIBUTING.md but didn't really found a suitable section for this.

ACKs for top commit:
  tcharding:
    utACK b3b57518a0
  apoelstra:
    ACK b3b57518a0

Tree-SHA512: 7c077ee6569d38cf4c518cd5003ba0c09fdf7f98f4fb14fd28b49eb2e1b43eec7833de7abd1e35b9b14451f37de8e36a740a6445e3a5feb34a79cbfb7e63ee9f

contrib/release.sh

@@ -9,6 +9,16 @@ main () {
     for crate in "internals" "hashes" "bitcoin"; do
         if release_changes $crate; then
             echo "$crate has changes implying this is a release PR, checking if we can publish ..."
+
+            # Check if there is any mention of NEXT_RELEASE which means the
+            # next version number should be filled in.
+            if grep -qr NEXT_RELEASE ./$crate; then
+                echo Version number needs to be filled in following places:
+                grep -r NEXT_RELEASE ./$crate
+                exit 1
+            fi
+
+            # Then try to dry-run cargo publish
             publish_dry_run $crate
         fi
     done