lang/spidermonkey91: limit Python version to 3.7-3.10 (+)

Old firefox engine still have harcoded 'rU' as file mode for 'fopen()'
'U' is default and deprecated since python-3.3, becomes a failure in 3.11.

Instead of patching dozen files, limit python to 3.7-3.10 as it used only for configure stage.

Approved by:	portmgr blanket

lang/spidermonkey91/Makefile

@@ -22,7 +22,7 @@ LIB_DEPENDS=	libffi.so:devel/libffi \
 		libnspr4.so:devel/nspr
 
 USES=		compiler:c++17-lang gmake localbase pathfix pkgconfig \
-		python:build readline tar:xz
+		python:3.7-3.10,build readline tar:xz
 USE_LDCONFIG=	yes
 SP_VER=		91
 HAS_CONFIGURE=	yes