Avoid backports import

Author: krlmlr

DESCRIPTION

@@ -16,8 +16,6 @@ URL: https://rprojroot.r-lib.org/,
 BugReports: https://github.com/r-lib/rprojroot/issues
 Depends:
     R (>= 3.0.0)
-Imports:
-    backports
 Suggests:
     knitr,
     lifecycle,

NAMESPACE

@@ -37,6 +37,5 @@ export(thisfile_knit)
 export(thisfile_r)
 export(thisfile_rscript)
 export(thisfile_source)
-import(backports)
 importFrom(utils,str)
 importFrom(utils,tail)

R/rprojroot-package.R

@@ -10,5 +10,4 @@
 #' root_fun <- is_r_package$make_fix_file()
 #' root_fun("NAMESPACE")
 #' }
-#' @import backports
 "_PACKAGE"