Don't check whether gnuplot is present in $PATH, because we know it is.

diff --git a/eazy-gnuplot.asd b/eazy-gnuplot.asd
index 7b1c09b..4657cd6 100644
--- a/eazy-gnuplot.asd
+++ b/eazy-gnuplot.asd
@@ -37,7 +37,4 @@
                                :fill-pointer t)))
           (setf (fill-pointer seq) (read-sequence seq stream))
           seq)))
-  :perform (load-op :before (op c)
-                    (unless (zerop (nth-value 2 (uiop:run-program "which gnuplot" :ignore-error-status t)))
-                      (warn "Could not find GNUPLOT in $PATH")))
   :in-order-to ((test-op (test-op eazy-gnuplot.test))))
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<tr><td><span title='2022-05-28 22:01:09 +0300'>2022-05-28</span></td><td><a href='/guix/commit/gnu/packages/patches/libtool-skip-tests2.patch?id=1da2834720c99c3707d17e4bf12e409b1a374b29'>gnu: libtool and libltdl: Update to 2.4.7.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/autotools.scm (libtool, libltdl): Update to 2.4.7.
[arguments]: Remove trailing #t from phases. Remove unnecessary file
field from find-files.
(libltdl)[arguments]: Remove trailing #t.
* gnu/packages/patches/libtool-skip-tests2.patch: Update patch.
</span></span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2022-01-11 12:43:37 +0200'>2022-01-11</span></td><td><a href='/guix/commit/gnu/packages/patches/libtool-skip-tests2.patch?id=6ba510d76d6847065be725e958718002f3b13c7a'>gnu: libtool: Skip the nopic tests on riscv.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/patches/libtool-skip-tests2.patch: Adjust to add riscv to
skipped nopic tests.
</span></span></td><td>Efraim Flashner</td></tr>