update to go 15

Author: codemodify

go.mod

@@ -1,5 +1,5 @@
 module github.com/remoteit/systemkit-crashproof
 
-go 1.13
+go 1.15
 
-require github.com/remoteit/systemkit-callstack v1.0.3
+require github.com/remoteit/systemkit-callstack v1.0.4

go.sum

@@ -1,2 +1,2 @@
-github.com/remoteit/systemkit-callstack v1.0.3 h1:y2oJxrEFf+nW1YsXveid4lYLgHM2pVscTk5TBPT/+Og=
-github.com/remoteit/systemkit-callstack v1.0.3/go.mod h1:RzTpHtdVnY0MmwrWmNNzUMidL9LtwImB5ckAhZp1aM0=
+github.com/remoteit/systemkit-callstack v1.0.4 h1:ZTjLxj/1OqjAsZdrliofmodyf2Fp+XH4RPjtsJ4j5kY=
+github.com/remoteit/systemkit-callstack v1.0.4/go.mod h1:e/Oak5ajApTt2xhcDRczSjZR1s88eg1fYBQqqr+1m4Q=