Allow needless-lifetimes (#363)

Fix a nightly clippy lint

fitsio/src/errors.rs

@@ -121,7 +121,7 @@ impl ::std::convert::From<IntoStringError> for Error {
 use crate::fitsfile::FitsFile;
 type PoisonError<'a> = sync::PoisonError<sync::MutexGuard<'a, FitsFile>>;
 
-impl<'a> ::std::convert::From<PoisonError<'a>> for Error {
+impl ::std::convert::From<PoisonError<'_>> for Error {
     fn from(_e: PoisonError) -> Self {
         Error::UnlockError
     }

fitsio/src/hdu.rs

@@ -960,7 +960,7 @@ pub struct FitsHduIterator<'a> {
     pub(crate) fits_file: &'a mut FitsFile,
 }
 
-impl<'a> Iterator for FitsHduIterator<'a> {
+impl Iterator for FitsHduIterator<'_> {
     type Item = FitsHdu;
 
     fn next(&mut self) -> Option<Self::Item> {
@@ -1002,7 +1002,7 @@ impl DescribesHdu for usize {
     }
 }
 
-impl<'a> DescribesHdu for &'a str {
+impl DescribesHdu for &'_ str {
     fn change_hdu(&self, f: &mut FitsFile) -> Result<()> {
         let mut status = 0;
         let c_hdu_name = ffi::CString::new(*self)?;

fitsio/src/headers/mod.rs

@@ -287,7 +287,7 @@ impl WritesKey for String {
     }
 }
 
-impl<'a> WritesKey for &'a str {
+impl WritesKey for &'_ str {
     fn write_key(f: &mut FitsFile, name: &str, value: Self) -> Result<()> {
         let c_name = ffi::CString::new(name)?;
         let c_value = ffi::CString::new(value)?;

fitsio/src/tables.rs

@@ -772,7 +772,7 @@ impl DescribesColumnLocation for usize {
     }
 }
 
-impl<'a> DescribesColumnLocation for &'a str {
+impl DescribesColumnLocation for &'_ str {
     fn get_column_no(&self, hdu: &FitsHdu, fits_file: &mut FitsFile) -> Result<i32> {
         match hdu.get_column_no(fits_file, *self) {
             Ok(value) => Ok(value as _),
@@ -849,7 +849,7 @@ impl<'a> ColumnIterator<'a> {
     }
 }
 
-impl<'a> Iterator for ColumnIterator<'a> {
+impl Iterator for ColumnIterator<'_> {
     type Item = Column;
 
     fn next(&mut self) -> Option<Self::Item> {