sagemathgh-36926: conda: Pin compilers until sagemath#36840 is fixed

    
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This is a workaround for:
- sagemath#36840

Cherry-picked from sagemath#36372

Author: @tobiasdiez

Reviewer: @mkoeppe

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### ⌛ Dependencies

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- Depends on sagemath#36910 (merged here to fix merge conflict)

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URL: sagemath#36926
Reported by: Matthias Köppe
Reviewer(s):

build/pkgs/_prereq/distros/conda.txt

@@ -7,7 +7,7 @@
 # One package per line. No need to escape special characters.
 # Everything on a line after a # character is ignored.
 #
-compilers
+compilers<=1.6.0 # 1.7 pulls in c-compiler v.16
 make
 m4
 perl