[LyX/master] LyXHTML: fix the content-type attribute, it must be lower case (enforced for HTML5).

[Thibaut Cuvelier]

commit cabb12ba51de713d5162ed2ef956d71b3974acc0
Author: Thibaut Cuvelier <tcuvelier at lyx.org>
Date:   Sat Jan 7 03:33:48 2023 +0100

    LyXHTML: fix the content-type attribute, it must be lower case (enforced for HTML5).
---
 src/Buffer.cpp |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/src/Buffer.cpp b/src/Buffer.cpp
index 907026e..8b95a46 100644
--- a/src/Buffer.cpp
+++ b/src/Buffer.cpp
@@ -2257,7 +2257,7 @@ Buffer::ExportStatus Buffer::writeLyXHTMLSource(odocstream & os,
 		   << "<meta name=\"GENERATOR\" content=\"" << PACKAGE_STRING << "\" />\n"
 		   << "<meta charset=\"UTF-8\" />\n"
 		   // FIXME Presumably need to set this right
-		   << "<meta http-equiv=\"Content-type\" content=\"text/html;charset=UTF-8\" />\n";
+		   << "<meta http-equiv=\"content-type\" content=\"text/html;charset=UTF-8\" />\n";
 
 		docstring const & doctitle = features.htmlTitle();
 		os << "<title>"