docs: store the release-calendar information in csv (and fix tests)

Restructured text (and markdown) is painful to programatically
manipulate, most python parsers are geared towards writing markdown and
generating html. I'd like to move the calendar updates to being
scripted, as such using csv to store them will be convenient. This also
allows us to simplify our scripting that manipulates the table
considerably.

Acked-by: Eric Engestrom <eric@engestrom.ch>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8341>

bin/post_version.py

@@ -22,6 +22,7 @@
 """Update the main page, release notes, and calendar."""
 
 import argparse
+import csv
 import pathlib
 import subprocess
 
@@ -52,30 +53,24 @@ def update_release_notes(version: str) -> None:
 
 
 def update_calendar(version: str) -> None:
-    p = pathlib.Path('docs') / 'release-calendar.rst'
+    p = pathlib.Path('docs') / 'release-calendar.csv'
 
-    with open(p, 'r') as f:
-        calendar = f.readlines()
+    with p.open('r') as f:
+        calendar = csv.reader(f)
 
-    branch = ''
-    skip_line = False
-    new_calendar = []
-    for line in calendar:
-        if version in line:
-            branch = line.split('|')[1].strip()
-            skip_line = True
-        elif skip_line:
-            skip_line = False
-        elif branch:
-            # Put the branch number back on the next line
-            new_calendar.append(line[:2] + branch + line[len(branch) + 2:])
-            branch = ''
-        else:
-            new_calendar.append(line)
+    branch = None
+    for i, line in enumerate(calendar):
+        if line[2] == version:
+            if line[0]:
+                branch = line[0]
+            break
+    if branch is not None:
+        calendar[i + 1][0] = branch
+    del calendar[i]
 
-    with open(p, 'w') as f:
-        for line in new_calendar:
-            f.write(line)
+    with p.open('w') as f:
+        writer = csv.writer(f)
+        writer.writerows(calendar)
 
     subprocess.run(['git', 'add', p])