[Data] Deprecate silane.yaml

This file is of unknown provenance, contains discontinuous thermo
data, and is no longer used in any examples or tests.

data/silane.yaml

@@ -17,6 +17,10 @@ phases:
     SI3H8, SI2, SI3]
   kinetics: gas
   state: {T: 300.0, P: 1 atm}
+  deprecated: >|
+    The input file 'silane.yaml' is deprecated and will be removed after Cantera 2.6.
+    The source of the data is unknown, and the NASA polynomials for several species
+    contain discontinuities.
 
 species:
 - name: H2