[misc] fix blog post generator quirks

[wesleywright]

While preparing the 1.15 release blog posts, I noticed a few quirks with our maarkdown converter:

• We treat any \n followed by a capital letter as a new paragraph, which can cause too many <p> tags to be inserted at times (a common cause in this blog post was a line break followed by the word "PR").
• Using multiple consecutive backticks for an inline code section is valid markdown (it's commonly used for strings where you need to include single backticks, eg ``a string with a single ` :)``), but our script was confused by this and generated lots of erroneous <tt> sections where they didn't belong.
• Including a #\d in the middle of a word caused the script to assume it was a PR that it should link. In this specific case, the changelog contains several occurrences of mypy_mypyc-wheels#<PR number>, which the script was stomping on.

This PR contains some minor tweaks for the blog post generation script that attempt to address these quirks.

[svalentin]

Please test on the previous release’s release notes to make sure it still looks correct as an extra validation

[wesleywright]

1.14 only seems to be affected by line break changes:

diff -u *.html.old *.html.new
--- 1.14-blog-post.html.old     2025-02-05 14:29:34
+++ 1.14-blog-post.html.new     2025-02-05 14:29:27
@@ -7,8 +7,8 @@
 <h1>Mypy 1.14 Released</h1>
 
 <p>We’ve just uploaded mypy 1.14 to the Python Package Index (<a href="https://pypi.org/project/mypy/">PyPI</a>).
-<p>Mypy is a static type checker for Python. This release includes new features and bug fixes.
-<p>You can install it as follows:
+Mypy is a static type checker for Python. This release includes new features and bug fixes.
+You can install it as follows:
 
 <pre><code>python3 -m pip install -U mypy
 </code></pre>
\ No newline at end of file
@@ -60,7 +60,7 @@
 </code></pre>
 
 <p>Contributed by Terence Honles (PR <a href="https://github.com/python/mypy/pull/17207">17207</a>) and
-<p>Shantanu Jain (PR <a href="https://github.com/python/mypy/pull/18068">18068</a>).
+Shantanu Jain (PR <a href="https://github.com/python/mypy/pull/18068">18068</a>).
 
 <h2>Support for @deprecated Decorator (PEP 702)</h2>
 
\ No newline at end of file
@@ -71,7 +71,7 @@
 
 <p>You can enable the error code via <tt>--enable-error-code=deprecated</tt> on the mypy
 command line or <tt>enable_error_code = deprecated</tt> in the mypy config file.
-<p>Use the command line flag <tt>--report-deprecated-as-note</tt> or config file option
+Use the command line flag <tt>--report-deprecated-as-note</tt> or config file option
 <tt>report_deprecated_as_note=True</tt> to turn all such errors into notes.
 
 <p>Deprecation errors will be enabled by default in a future mypy version.
\ No newline at end of file

I saw one minor discrepancy with spacing on the 1.11 release post, which I'll push a fix for now (just adding back the extra whitespace character that my change ate).