Always provide the same date and time in 'Py_GetBuildInfo'.
This is the information shown at the REPL and in 'sys.version'.
We cannot pass it in CPPFLAGS due to whitespace in the DATE string.

--- a/Modules/getbuildinfo.c
+++ b/Modules/getbuildinfo.c
@@ -4,6 +4,10 @@
 #include <stdio.h>
 #endif
 
+/* Deterministic date and time.  */
+#define DATE "Jan  1 1970"
+#define TIME "00:00:01"
+
 #ifndef DATE
 #ifdef __DATE__
 #define DATE __DATE__
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<tr><td><span title='2022-11-22 08:37:25 +0100'>2022-11-22</span></td><td><a href='/guix/commit/gnu/packages/xorg.scm?id=256a63ce0b8dae05a44ccdadf682f23a8be5396b'>gnu: libwindowswm: Add missing input.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/xorg.scm (libwindowswm)[inputs]: Add WINDOWSWMPROTO.
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'install-bdf2psf phase to install bdf2psf and its manpage.
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