golang: tests: Adjust golang_test_defer_excchain.txt-pytest golden to support Windows

Apparently on Windows pytest detects terminal width differently than on
Linux/macOS and the test fails as

    E           Failed: not equal:
    E           Differences (unified diff with -expected +actual):
    E               @@ -1,5 +1,12 @@
    E               -...
    E               -_____________________________________ main _____________________________________
    E               -../__init__.py:...: in _
    E               +============================= test session starts =============================
    E               +platform win32 -- Python 3.10.11, pytest-7.3.1, pluggy-1.0.0
    E               +rootdir: PYGOLANG
    E               +collected 1 item
    E               +<BLANKLINE>
    E               +golang_test_defer_excchain.py F                                          [100%]
    E               +<BLANKLINE>
    E               +================================== FAILURES ===================================
    E               +____________________________________ main _____________________________________
    E               +../__init__.py:106: in _
    E                    return f(*argv, **kw)
    E                golang_test_defer_excchain.py:42: in main
    E               @@ -8,6 +15,6 @@
    E                <BLANKLINE>
    E                During handling of the above exception, another exception occurred:
    E               -../__init__.py:...: in __exit__
    E               -    ...
    E               +../__init__.py:183: in __exit__
    E               +    d()
    E                golang_test_defer_excchain.py:31: in d1
    E                    raise RuntimeError("d1: aaa")
    E               @@ -15,9 +22,9 @@
    E                <BLANKLINE>
    E                During handling of the above exception, another exception occurred:
    E               -../__init__.py:...: in __exit__
    E               -    ...
    E               +../__init__.py:183: in __exit__
    E               +    d()
    E                golang_test_defer_excchain.py:33: in d2
    E                    1/0
    E               -E   ZeroDivisionError: ...
    E               +E   ZeroDivisionError: division by zero
    E                <BLANKLINE>
    E                During handling of the above exception, another exception occurred:
    E               @@ -25,3 +32,5 @@
    E                    raise RuntimeError("d3: bbb")
    E                E   RuntimeError: d3: bbb
    E               -=========================== ...
    E               +=========================== short test summary info ===========================
    E               +FAILED golang_test_defer_excchain.py::main - RuntimeError: d3: bbb
    E               +============================== 1 failed in 1.45s ==============================

-> Fix it by not requesting header to be of particular width.

golang/testprog/golang_test_defer_excchain.txt-pytest

 ...
-_____________________________________ main _____________________________________
+...________________ main ________________...
 ../__init__.py:...: in _
     return f(*argv, **kw)
 golang_test_defer_excchain.py:42: in main