chore(ci): fix publish-gh-release failure

When generating the changelog heading for the new version, scriv uses an
em dash (—) to separate the version from the date, not a hypen dash. Do not
 try to match it when extracting the notes for the release.

Update the existing entry in CHANGELOG.md to use an em dash.

Author: agateau-gg

CHANGELOG.md

@@ -10,7 +10,7 @@
 
 <a id='changelog-1.5.0'></a>
 
-## 1.5.0 - 2022-11-28
+## 1.5.0 — 2022-11-28
 
 ### Added
 

scripts/release

@@ -201,9 +201,7 @@ def get_release_notes(version: str) -> str:
 
     # Extract changes from CHANGELOG.md
     changes = CHANGELOG_PATH.read_text()
-    start_match = re.search(
-        f"^## {re.escape(version)} - .*", changes, flags=re.MULTILINE
-    )
+    start_match = re.search(f"^## {re.escape(version)} .*", changes, flags=re.MULTILINE)
     assert start_match
     start_pos = start_match.end() + 1