Add banners for workshops (#1673)

* Add banners for workshops

JuliaHEP plus the WLCG-HSF workshop

* Fix filenames

* Tiny format change!

announcements/_posts/2024/2024-09-30-JuliaHEP2024.md

@@ -1,5 +1,5 @@
 ---
-title: JuliaHEP 2023, 30 September - 4 October 2024
+title: JuliaHEP 2024, 30 September - 4 October 2024
 author: Graeme Stewart
 layout: newsletter
 symbol: glyphicon-calendar

announcements/_posts/2025/2025-02-10-JuliaHEP.md

@@ -0,0 +1,11 @@
+---
+title: JuliaHEP 2025, 28-31 July 2025
+author: Graeme Stewart
+layout: newsletter
+symbol: glyphicon-calendar
+link: https://indico.cern.ch/e/juliahep2025
+until: 2025-07-31
+---
+
+We will have the third **JuliaHEP** workshop at Princeton from the 28th of July until the 31st of July 2025. The workshop will consist of hackathons, presentations and tutorials.
+

announcements/_posts/2025/2025-02-10-WLCG-HSF.md

@@ -0,0 +1,22 @@
+---
+title:  WLCG-HSF Workshop, 5-9 May, 2025
+author: Graeme Stewart
+layout: newsletter
+symbol: glyphicon-calendar
+link: https://indico.cern.ch/e/wlcg-hsf-2025
+until: 2025-05-09
+---
+
+We are happy to announce that registration is now open for the next joint WLCG/HSF workshop. The workshop will be held at IJCLab, Orsay, from the 5th-9th May 2025:
+
+https://indico.cern.ch/e/wlcg-hsf-2025
+
+You are warmly invited to submit your abstracts on "Software Sustainability and Community Software".
+
+*** The deadline for abstract submission is MARCH 9th ***
+
+We will send acceptance notifications on MARCH 14th; the registration fee will increase on APRIL 11TH.
+
+The abstract themes are broadly defined: Sustainability is an issue for software in many ways, from software efficiency and the environmental footprint, to software maintenance and preservation.  Likewise, community software spans everything from software packages and tools that support multiple experiments, to training initiatives and community support structures.
+
+We very much look forward to seeing you in IJCLab in May!