Fix french mistranslation

Close #5680
(cherry picked from commit ddb5191fec115d65341f5429ce2a0a426899feeb)
Signed-off-by: Jean-Baptiste Kempf <jb@videolan.org>

po/fr.po

@@ -2911,7 +2911,7 @@ msgstr ""
 
 #: src/libvlc-module.c:840
 msgid "Subpictures source module"
-msgstr "Module d'incrustations"
+msgstr "Module de source d'incrustations"
 
 #: src/libvlc-module.c:842
 msgid ""
@@ -2923,7 +2923,7 @@ msgstr ""
 
 #: src/libvlc-module.c:845
 msgid "Subpictures filter module"
-msgstr "Module d'incrustations"
+msgstr "Module de filtre d'incrustations"
 
 #: src/libvlc-module.c:847
 msgid ""