Reduced size of test_wavedecomposition

In order to speed up our CI pipeline,
#285 suggested
to reduce the size of a number of tests, test_wavedecomposition
being one of them. The tests are now running with a smaller
input data.

pytests/test_wavedecomposition.py

@@ -20,7 +20,7 @@
     "ny": 11,
     "ot": 0,
     "dt": 0.004,
-    "nt": 50,
+    "nt": 30,
     "f0": 40,
 }
 
@@ -32,10 +32,10 @@
 # separation params
 vel_sep = 1000.0  # velocity at separation level
 rho_sep = 1000.0  # density at separation level
-critical = 0.9
-ntaper = 41
-nfftf = 2 ** 8
-nfftk = 2 ** 7
+critical = 0.99
+ntaper = 5
+nfftf = 2 ** 6
+nfftk = 2 ** 6
 
 # axes and wavelet
 t, t2, x, y = makeaxis(PAR)