Update Video Templates To Match Website Theme

The templates shown in the beginning of each video in the Learning Path used to match the general theme of the InnerSource Commons website. The website got a fresh new look at some point, but, the video templates have not.

The website's new theme uses teal (#0CA7A7) as the main action color and PT Sans as the font. The logo has also been refreshed to have a smaller outer border.

At a bare minimum, it would be great if the existing templates could use the new logo, colors, and fonts. If we're feeling slightly more adventurous, we could go for a look that matches overlays found in other areas of the website (see the Announcements section for an example). And if we're feeling really ambitious we could design something totally new and unique and use that.

It's totally up to whoever takes up this issue how they want to go about solving it, so long as they collaborate with the group as they go.

Keep in mind that any template we use will also need to be applied to the static images we use for workbooks (or some variation of it at least).

@lenucksi pointed out the original templates, created by @RJPlog, are located here:
https://github.com/InnerSourceCommons/InnerSourceLearningPath/blob/main/assets/thumbnails/thumbnail_template.odg

Comienza con assets/thumbnails/thumbnail_template.odg y compáralo con el tema actual del sitio web, especialmente con la sección Announcements. Revisa las plantillas de vídeo existentes y las imágenes estáticas del workbook; después, define un tratamiento coherente utilizando el logotipo actualizado, el color teal y PT Sans. Se considerará terminado cuando el estilo de plantilla seleccionado se haya aplicado tanto a los vídeos como a las imágenes del workbook y se haya revisado con el grupo.