Release 0.1.3 [skip ci]

[Diff since v0.1.1](v0.1.1...v0.1.2)

- block-based I/O
- unit conversion
- ConfParser

**Merged pull requests:**
- Elehcim gadget2 particle (#12) (@islent)
- CompatHelper: add new compat entry for ConfParser at version 0.1, (keep existing compat) (#13) (@github-actions[bot])
- CompatHelper: add new compat entry for Combinatorics at version 1, (keep existing compat) (#14) (@github-actions[bot])

- FileIO interfaces

- StructArray
- format2
- acc, pot I/O
- file unit conversion

**Closed issues:**
- Error with gadget2 file (#1)

**Merged pull requests:**
- CompatHelper: bump compat for "StaticArrays" to "1.0" (#2) (@github-actions[bot])
- CompatHelper: bump compat for "CSV" to "0.8" (#3) (@github-actions[bot])
- CompatHelper: bump compat for "JLD2" to "0.3" (#4) (@github-actions[bot])
- CompatHelper: bump compat for "HDF5" to "0.14" (#5) (@github-actions[bot])
- CompatHelper: bump compat for "HDF5" to "0.15" (#6) (@github-actions[bot])
- CompatHelper: bump compat for "JLD2" to "0.4" (#7) (@github-actions[bot])
- Fix Gadget2 read and units (#8) (@elehcim)