converted mpl timestamps to UTC (#765)

* remove named timezone from mpl file

Follow up to  #764,

* converted timestamps to utc

Author: story645

calendars/matplotlib.yaml

@@ -1,5 +1,4 @@
 name: Matplotlib Community Calendar
-timezone: Europe/Berlin
 events:
   - summary: Matplotlib — Plot Plotting (open project call)
     description: |
@@ -9,8 +8,8 @@ events:
 
       Meeting notes and agenda: https://hackmd.io/@matplotlib
 
-    begin: 2022-03-24 21:00:00 +02:00
-    end: 2022-03-24 22:00:00 +02:00
+    begin: 2022-03-24 19:00:00 +00:00
+    end: 2022-03-24 20:00:00 +00:00
     url: https://zoom.us/j/384435716?pwd=WFpxVWxoYXArTDFzN1lWaHNoOE8xZz09
     ics: RRULE:FREQ=WEEKLY;BYDAY=TH
 
@@ -24,8 +23,8 @@ events:
 
       Meeting notes: https://hackmd.io/@matplotlib
 
-    begin: 2023-02-07 19:00:00 +02:00
-    end: 2023-02-07 20:00:00 +02:00
+    begin: 2023-02-07 17:00:00 +00:00
+    end: 2023-02-07 18:00:00 +00:00
     url: https://numfocus-org.zoom.us/j/88077871096?pwd=bTxkJRug4Lmr8AiR9jNyntxBS4yGDe.1
     ics: RRULE:FREQ=MONTHLY;BYDAY=1TU;INTERVAL=2
 
@@ -39,8 +38,8 @@ events:
 
       Meeting notes: https://hackmd.io/@matplotlib
 
-    begin: 2023-03-07 13:00:00 +02:00
-    end: 2023-03-07 14:00:00 +02:00
+    begin: 2023-03-07 11:00:00 +00:00
+    end: 2023-03-07 12:00:00 +00:00
     url: https://numfocus-org.zoom.us/j/88077871096?pwd=bTxkJRug4Lmr8AiR9jNyntxBS4yGDe.1
     ics: RRULE:FREQ=MONTHLY;BYDAY=1TU;INTERVAL=2
 
@@ -52,7 +51,7 @@ events:
 
       Meeting notes: https://hackmd.io/@matplotlib/dwg
 
-    begin: 2023-12-15 19:00:00 +02:00
-    end: 2023-12-15 20:00:00 +02:00
+    begin: 2023-12-15 17:00:00 +00:00
+    end: 2023-12-15 18:00:00 +00:00
     url: https://us06web.zoom.us/j/81285851006?pwd=Tks2QjRkNWh5NGw0TmU1RUwwOVluZz09
     ics: RRULE:FREQ=WEEKLY;BYDAY=FR;INTERVAL=2