sagemathgh-38765: Fix time limitation in magma_free docstring

    
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Change time limitation from 20 to 120 in the documentation of
magma_free.
<!-- v Why is this change required? What problem does it solve? -->

> Calculations are restricted to 120 seconds.
http://magma.maths.usyd.edu.au/calc/

> <max_time>120</max_time>
http://magma.maths.usyd.edu.au/xml/calculator.xml?input=Factorization(15
)


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URL: sagemath#38765
Reported by: Eloi Torrents
Reviewer(s): Travis Scrimshaw, Vincent Macri

src/sage/interfaces/magma_free.py

@@ -26,8 +26,10 @@ def magma_free_eval(code, strip=True, columns=0):
     Use the free online MAGMA calculator to evaluate the given
     input code and return the answer as a string.
 
-    LIMITATIONS: The code must evaluate in at most 20 seconds
-    and there is a limitation on the amount of RAM.
+    .. WARNING::
+
+        The code must evaluate in at most 120 seconds
+        and there is a limitation on the amount of RAM.
 
     EXAMPLES::