Handle spaces after ± symbol in complex value parsing

Update regex to allow optional whitespace between sign and value: ([±+-]?)\s*
This now handles cases like "± 0 + 0j" in addition to "±0 + 0j"

Co-authored-by: ev-br <2133832+ev-br@users.noreply.github.com>

Author: Copilot

array_api_tests/test_special_cases.py

@@ -751,9 +751,9 @@ class UnaryCase(Case):
 r_complex_case = re.compile(r"If ``a`` is (.+) and ``b`` is (.+), the result is (.+)")
 # Matches complex values like "+0 + 0j", "NaN + NaN j", "infinity + NaN j", "πj/2", "3πj/4"
 # Two formats: 1) πj/N expressions where j is part of the coefficient, 2) plain values followed by j
-# Also handles ± symbol for unspecified signs
+# Also handles ± symbol for unspecified signs (with or without spaces after the sign)
 r_complex_value = re.compile(
-    r"([±+-]?)([^\s]+)\s*([±+-])\s*(?:(\d*πj(?:/\d+)?)|([^\s]+))\s*j?"
+    r"([±+-]?)\s*([^\s]+)\s*([±+-])\s*(?:(\d*πj(?:/\d+)?)|([^\s]+))\s*j?"
 )