fix: Remove the blank line inserted between code blocks and captions

This change is part of the fix for
#645. The good thing is
that there's no functional change in how Hugo/GoldMark (tested on Hugo
v0.99.1) render these Markdown files after the change.

So, to the user, it will be just a cosmetic change, that now there are
no blank lines between code blocks and their captions.

ox-hugo.el

@@ -3436,7 +3436,7 @@ their Hugo site's config."
                                     (caption-str
                                      (org-html-convert-special-strings ;Interpret em-dash, en-dash, etc.
                                       (org-export-data-with-backend caption 'html info))))
-                               (format (concat "\n\n<div class=\"src-block-caption\">\n"
+                               (format (concat "\n<div class=\"src-block-caption\">\n"
                                                "  <span class=\"src-block-number\">%s:</span>\n"
                                                "  %s\n"
                                                "</div>")

test/site/content/posts/inlined-svg.md

@@ -65,7 +65,6 @@ style="stroke:#A80036;stroke-width:1.0;"/></g></svg>
 class A
 url of A is [[https://example.org/]]
 ```
-
 <div class="src-block-caption">
   <span class="src-block-number">Code Snippet 1:</span>
   My class diagram

test/site/content/posts/links-to-source-blocks.md

@@ -52,7 +52,6 @@ that the link jump is evident):
 ````emacs-lisp
 (message "Hello")
 ````
-
 <div class="src-block-caption">
   <span class="src-block-number"><a href="#code-snippet--hello">Code Snippet 1</a>:</span>
   Hello
@@ -116,7 +115,6 @@ blandit in.
 ````emacs-lisp
 (message "Hello again")
 ````
-
 <div class="src-block-caption">
   <span class="src-block-number"><a href="#code-snippet--helloagain">Code Snippet 2</a>:</span>
   Hello Again

test/site/content/posts/source-block-caption.md

@@ -7,7 +7,6 @@ draft = false
 ```makefile
 prefix = /dir/where/you/want/to/install/org # Default: /usr/share
 ```
-
 <div class="src-block-caption">
   <span class="src-block-number">Code Snippet 1:</span>
   Prefix value in <code>local.mk</code>
@@ -16,7 +15,6 @@ prefix = /dir/where/you/want/to/install/org # Default: /usr/share
 ```emacs-lisp
 (message "hello")
 ```
-
 <div class="src-block-caption">
   <span class="src-block-number">Code Snippet 2:</span>
   Hello &#x2014; Caption with em-dash &#x2013; and &#x2013; en-dash

test/site/content/singles/links-to-org-elements.md

@@ -62,7 +62,6 @@ that the link jump is evident):
 ````emacs-lisp
 (message "Hello")
 ````
-
 <div class="src-block-caption">
   <span class="src-block-number"><a href="#code-snippet--hello">Programmlisting 1</a>:</span>
   Hello
@@ -126,7 +125,6 @@ blandit in.
 ````emacs-lisp
 (message "Hello again")
 ````
-
 <div class="src-block-caption">
   <span class="src-block-number"><a href="#code-snippet--helloagain">Programmlisting 2</a>:</span>
   Hello Again