gh-39827: fix random doctest error in `src/sage/data_structures/bitset.pyx`
    
Fixes #39826.

Bitset cannot be build from an empty list. We change the doctest to pass
lists with at least 1 element.

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URL: #39827
Reported by: David Coudert
Reviewer(s): Frédéric Chapoton

Author: Release Manager

src/sage/data_structures/bitset.pyx

@@ -164,7 +164,7 @@ cdef class FrozenBitset:
 
     Try a random bitset::
 
-        sage: a = Bitset(randint(0, 1) for n in range(1, randint(1, 10^4)))
+        sage: a = Bitset(randint(0, 1) for n in range(randint(1, 10^4)))
         sage: b = FrozenBitset(a); c = FrozenBitset(b)
         sage: bitcmp(a, b, c)
         True
@@ -239,7 +239,7 @@ cdef class FrozenBitset:
 
     A random iterable, with all duplicate elements removed::
 
-        sage: L = [randint(0, 100) for n in range(1, randint(1, 10^4))]
+        sage: L = [randint(0, 100) for n in range(randint(1, 10^4))]
         sage: FrozenBitset(L) == FrozenBitset(list(set(L)))
         True
         sage: FrozenBitset(tuple(L)) == FrozenBitset(tuple(set(L)))